Vascular Delay Revisited

Hydrogels containing KYNA promote angiogenesis and inhibit inflammation to improve the survival rate of multi-territory perforator flaps

BACKGROUND

A new spray adhesive (KYNA-PF127) was established through the combination of thermosensitive hydrogel (Pluronic F127) and KYNA, aimed to investigate the effect of KYNA-PF127 on multi-territory perforator flaps and its possible molecular mechanism.

MATERIALS AND METHODS

36 SD male rats with 250-300 g were randomly divided into 3 groups (n = 12): control group, blank glue group and KYNA-PF127 group. KYNA-PF127 hydrogel was prepared and characterized for its morphology and properties using scanning electron microscopy. CCK-8 assay, scratch wound assay, transwell assay, tube formation assay and Ki67 staining were used to study the effect of KYNA-PF127 on the proliferation, migration, and tube formation of HUVECs. VEGF and FGF2 were measured by qPCR to evaluate the angiogenesis capacity of HUVECs in vitro. In vivo, the effect of each group on the survival area of the cross-zone perforator flap was evaluated, and angiogenesis was evaluated by HE and immunofluorescence (CD31 and MMP-9). The effect of inflammation on skin collagen fibers was assessed by Masson. Immunohistochemistry (SOD1, IL-1β, TNF-α) was used to evaluate the effects of oxidative stress and inflammatory factors on multi-territory flaps.

RESULTS

KYNA-PF127 has good sustained release and biocompatibility at 25% concentration. KYNA-PF127 promoted the proliferation, migration, and angiogenesis of HUVECs in vitro. In vivo, the survival area of multi-territory perforator flaps and angiogenic capability have increased after KYNA-PF127 intervention. KYNA-PF127 could effectively reduce the oxidative stress and inflammation of multi-territory perforator flaps.

CONCLUSION

KYNA-PF127 promotes angiogenesis through its antioxidant stress and anti-inflammatory effects, and shows potential clinical value in promoting the survival viability and drug delivery of multi-territory perforator flaps.

Effects of pharmacological delay with roxadustat on multi-territory perforator flap survival in rats

Roxadustat (FG-4592) is a specific hypoxia-inducible factor (HIF) prolyl hydroxylase inhibitor. We investigated the effects of FG-4592 pretreatment on survival and second choke vessels of multi-territory perforator flaps in rats. In total, 72 rats were divided into two groups (n = 36 each): the experimental (FG-4592) group and the control group. FG-4592 was administered orally as a single dose of 60 mg/kg every other day; the first drug solution was administered to the animals 7 days before the surgical procedure. On postoperative day 7, the surviving flap area was calculated. At 12 h post-surgery, in the second choke zone in the flaps, macrovascular hinges were compared by angiography and imaging, and microvascular changes were assessed by histology. Laser Doppler imaging was used to evaluate flap perfusion at the second choke zone at 12 h and 7 days after surgery. At 7 days after surgery, the flap survival area and perfusion were significantly greater in rats given FG-4592 compared with controls. At 12 h after surgery, the diameter of macrovascular and microvascular vessels, nitric oxide content, perfusion, and the protein levels of HIF-1α and inducible nitric oxide synthase were also significantly greater in FG-4592-treated rats than controls. In conclusion, pretreatment with roxadustat may improve initial flap survival and dilate the second choke zone vessels in a multi-territory perforator flap.

Revisiting Bipedicled Flaps for Lower Extremity Distal Third Defects

BACKGROUND

Lower extremity reconstruction of the distal third of the leg is challenging. Free tissue transfer is the criterion standard. The COVID-19 pandemic encouraged seeking alternatives for resource consuming procedures. Bipedicled flaps are flaps with a dual-source subdermal perfusion. The purpose of this study was to assess outcomes of patients who had bipedicled flaps primary or auxiliary local flap for distal third leg/foot reconstruction.

METHODS

A retrospective review of patients undergoing lower extremity reconstruction (2020-2021) was performed. Inclusion criteria were patients older than 18 years with lower extremity wounds secondary to traumatic injury for which bipedicled flaps were used in the reconstruction. Exclusion criteria included lower extremity wounds secondary to peripheral vascular disease or diabetes.

RESULTS

Fourteen patients were included in the study. All patients had distal third of the leg/foot wounds, and 12 patients (87.5%) had concurrent leg fractures. In 8 patients (57.1%), the bipedicled flap was used to decrease the wound size and facilitate another concurrent flap: hemisoleus (21.4%), anterior tibialis muscle turnover (14.3%), medial plantar artery (14.3%), and posterior tibial artery perforator (14.3%). Mean wound size for bipedicle flaps used alone was 42.0 ± 18.3 cm2, whereas wounds that required a bipedicled flap with an additional flap were 69.9 ± 80.8 cm2 (P = 0.187). Two patients had partial flap necrosis (14.3%) but healed their defect. One patient had nonunion (7.1%). Limb salvage rate was 100%.

CONCLUSIONS

Bipedicled flaps can be used as an alternative to free flaps in distal third leg/foot defects in select patients. If distal extremity wounds cannot be covered with a bipedicled flap alone, the flap can be used an accessory flap to facilitate reconstruction with other local flaps.

Surgical flap delay to allow primary transabdominal transplantation of extended rectus abdominis myocutaneous flaps in increasingly complex pelvic wound reconstructions

Primary intra- or transabdominal transplantation of an extended rectus abdominis myocutaneous (ERAM) flap may help prevent surgical complications of pelvic resections. Surgical delay of the ERAM flap may help prevent intra-abdominal (partial) flap loss after transplantation in highly complex situations including previous irradiation. We report on the outcome of this approach and the risk-factors associated with an eventful outcome. From 2012 to 2020, 105 delayed ERAM flaps were consecutively applied immediately following extended pelvic resections after chemoradiation or hyperthermic intraperitoneal chemotherapy. We addressed the increased reconstructive demands by designing the flap in line with the 10^th rib and delaying the flap's skin island. All post-operative complications were assessed in light of patient-related or procedure-related potential risk-factors. Major complications occurred in 39 patients. These were correlated with surgery for residual or recurrent malignancy (p < 0.01), with tip necrosis after flap delay (p = 0.02), and with the use of a mesh to close the abdominal donor site (p < 0.01). (Partial) flap loss occurred in 4 cases. We observed a comparably high rate of major complications after ERAM transplantations for increasingly extending indications of perineal-pelvic resections. We consider this to be attributable to poorer patients' conditions and disease processes, rather than to flap viability. Delay of the flap allowed for the use of large and voluminous flaps with comparably little (partial) flap loss.

Delayed axial flaps for coverage of a fourth degree scalp burn

Although free tissue transfers may be required to cover wounds of the head and neck with bone involvement and exposure, options lower on the reconstructive ladder should still be considered during the planning process. We present a case of an elderly gentleman with a history of cardiovascular comorbidity and neck radiotherapy, who sustained a deep flame burn injury to his scalp. Two delayed axial flaps, based on the superficial temporal and supraorbital arteries respectively, were used to obtain durable coverage of this complex wound.

Mechanical Stress Improves Fat Graft Survival by Promoting Adipose-Derived Stem Cells Proliferation

Cell-assisted lipotransfer (CAL), defined as co-transplantation of aspirated fat with enrichment of adipose-derived stem cells (ASCs), is a novel technique for cosmetic and reconstructive surgery to overcome the low survival rate of traditional fat grafting. However, clinically approved techniques for increasing the potency of ASCs in CAL have not been developed yet. As a more clinically applicable method, we used mechanical stress to reinforce the potency of ASCs. Mechanical stress was applied to the inguinal fat pad by needling. Morphological and cellular changes in adipose tissues were examined by flow cytometric analysis 1, 3, 5, and 7 days after the procedure. The proliferation and adipogenesis potencies of ASCs were evaluated. CAL with ASCs treated with mechanical stress or sham control were performed, and engraftment was determined at 4 weeks post-operation. Flow cytometry analysis revealed that mechanical stress significantly increased the number as well as the frequency of ASC proliferation in fat. Proliferation assays and adipocyte-specific marker gene analysis revealed that mechanical stress promoted proliferation potential but did not affect the differentiation capacity of ASCs. Moreover, CAL with cells derived from mechanical stress-treated fat increased the engraftment. Our results indicate that mechanical stress may be a simple method for improving the efficacy of CAL by enhancing the proliferation potency of ASCs.

The Africa Temporal Scalp Flap: a novel flap for facial reconstruction

Although a number of flaps exist for nasal reconstruction, severe scarring of the forehead after burn injury led to the development of a novel two-stage flap based on the superficial temporal artery (STA). The Africa Temporal Scalp (ATS) flap is composed of an axial ascending part on the STA, and a descending anterior extension for reconstruction of the mid face. This is a retrospective analysis of all patients who underwent ATS Flap surgery on the MV Africa Mercy. During the 7.5-year period, the ATS flap was applied to 45 facial reconstructions, with a median age of 28 years (range 19 months to 51 years). The main indications were previous burn injury (n=27, 60%) and noma (n=15, 33.3%). The majority of the flaps were used to reconstruct the lower third of the nose (n=39, 86.7%), and the remaining 6 were for the lips or cheek. Experience allowed for earlier division than three weeks depending on the length of the flap, and the recipient site. There was one partial flap loss, one infection requiring revision, and two injuries to frontal branch of the facial nerve. The ATS flap is a novel two-stage flap that has proved especially versatile when forehead flaps are unavailable for nasal reconstruction due to extensive forehead scarring. The ATS flap reliably provides ample supple skin, and the donor site is effectively obscured from view, located in the periphery of the face.

The Language of Implant-based Breast Reconstruction: Can We Do Better?

The management of breast cancer has experienced tremendous changes in the last half-century. In today's multimodal approach to breast cancer, patients have the prospect of achieving a sense of normalcy after mastectomy thanks to advancements in oncology and breast reconstruction. Although the oncologic management of breast cancer has evolved over multiple centuries, implant-based breast reconstruction (IBBR) has only been around since the 1960s. The last half century has seen the conception of multiple techniques, novel devices, and new possibilities in hopes of achieving outcomes that are similar to or even better than the patient's premorbid state. However, with all these changes, a new problem has arisen-inconsistencies in the literature on how IBBR is described. In this article, we will discuss potential sources of confusion in the IBBR literature and lexicon, highlighting specific terms that may have multiple meanings or interpretations depending on perspective, context, and/or intent. As a first step toward clarifying what we perceive as a muddied landscape, we propose a naming convention for IBBR that centers around four important variables especially pertinent to IBBR-the type of mastectomy performed, the timing of reconstruction, the type of device that is placed, and the pocket location for device placement. We believe that adoption of a more standardized, consistent, and descriptive lexicon for IBBR will help provide clearer communication and easier comparisons in the literature so that we may continue to deliver the best outcomes for our patients.

Correlation of vascular change with TRPV1, TRPV4, and TRPA1 in a rat model of inferior gluteal artery perforator flap

Maximum survival area after perforator flap elevation is mainly achieved through vasodilation and angiogenesis, and endothelial Ca²⁺ signals play a pivotal role in both of them. Transient receptor potential (TRP) channels modulate many endothelial cell functions via mediating the extracellular Ca²⁺ entry. This study aims to investigate the correlation of TRPV4, TRPV1, and TRPA1 with vascular change after the inferior gluteal artery perforator flap elevation. A total of 50 adult male SD rats were used in this study. Ten rats were used in the part one to assess the flap viability on postoperative day 7. Twenty rats were used in the part two to evaluate blood flow change after flap elevation. The correlation of vascular change with TRPV1, TRPV4, and TRPA1 protein changes was investigated in 20 rats in the part three. The mean flap survival area percentage was 55 ± 5.7%. Blood flow in the overall flap and Zone II after the flap elevation markedly increased from the postoperative day 3. The most marked change of the vasodilation occurred on Days 3 and 5 after flap elevation. The angiogenesis occurred on Day 5 after flap elevation and the microvessel density peaked also on Day 5. Moreover, TRPA1 expression showed a trend towards continuous reduction over time. The expression of TRPV1 and TRPV4 reached the peak value on Day 3. The endothelial NO synthase expression showed an increasing trend at first, followed by a reduction over time, while VEGF expression reached the peak value on Day 3. The vascular changes after flap elevation might be associated with the changes in TRPV4, TRPV1, and TRPA1.

Dual efficacy of Fasudil at improvement of survival and reinnervation of flap through RhoA/ROCK/PI3K/Akt pathway

Fasudil is reported to be effective at protecting against ischaemic diseases, and at augmenting axon growth. In this study, we aim to evaluate its efficacy in promoting flap survival and reinnervation. Ninety-two Institute of Cancer Research (ICR) mice were used and divided into the control, Fasudil, LY294002, Fasudil+LY294002 groups, receiving a daily intraperitoneal injection of normal saline, Fasudil (10 mg/kg), LY294002 (5 mg/kg), and Fasudil (10 mg/kg) + LY294002 (5 mg/kg), respectively. On days 0 and 5, the blood perfusion and diameter of the iliolumbar artery in the pedicle of the flaps in the four groups were evaluated using laser speckling contrast imaging (LSCI). On day 5, the flaps were photographed and the necrosis rate of the flaps was calculated using Photoshop CS6. In addition, tissues were harvested from the flaps and divided into two parts. One part underwent routine cryosection and immunofluorescent staining using the antibody against CD31 for evaluation of the microvascular density in the four groups. In the other part, the expression of RhoA, ROCK1+2, p-CPI-17, p-MYPT, p-PTEN, p-PI3K, p-Akt, and vascular endothelial growth factor (VEGF) within the flaps were determined using western blotting. Moreover, at days 0, 7, 15, and 30 after flap surgery, the axons within the flaps were evaluated using immunofluorescent staining with the antibody against Neurofilament-200. It turned out that the necrosis rate was (24.4 ± 7.7)%, (5.2 ± 1.6)%, (29.8 ± 4.2)%, and (30.9 ± 7.1)%, respectively, in the control, Fasudil, LY294002, LY294002+Fasudil groups. There was a significant reduction in the necrosis rate of the flaps in the Fasudil group (P < .001). The LSCI and immunofluorescent staining demonstrated that Fasudil could significantly expand the diameter of the iliolumbar artery in the pedicle, boost the overall blood perfusion, and increase the microvascular density of the flaps in the Fasudil group (P < .05), which could all be abolished by PI3K inhibitor LY294002. On day 5, the expression of p-CPI-17, p-MYPT, and p-PTEN were downregulated, whereas pPI3K, p-Akt, and VEGF were upregulated in the Fasudil group (P < .001). As for reinnervation, Neurofilament-200 fluorescent staining revealed that at days 15 and 30 after flap harvest, only in the Fasudil group could new axons be observed. It can be concluded that Fasudil could simultaneously improve the survival and axon growth after flap harvest, a dual efficacy achieved by inhibition of the RhoA/ROCK pathway, which in turn activates /PI3K/AKT pathway.

The Influence of Topical Vasodilator-Induced Pharmacologic Delay on Cutaneous Flap Viability and Vascular Remodeling

BACKGROUND

Surgical delay is a well-described technique to improve survival of random and pedicled cutaneous flaps. The aim of this study was to test the topical agents minoxidil and iloprost as agents of pharmacologic delay to induce vascular remodeling and decrease overall flap necrosis as an alternative to surgical delay.

METHODS

Seven groups were studied (n = 8 in each group), including the following: vehicle, iloprost, or minoxidil before treatment only; vehicle, iloprost, or minoxidil before and after treatment; and a standard surgical delay group as a positive control. Surgical flaps (caudally based modified McFarlane myocutaneous skin flaps) were elevated after 14 days of pretreatment, reinset isotopically, and observed at various time points until postoperative day 7. Gross viability, histology, Doppler blood flow, perfusion imaging, tissue oxygenation measurement, and vascular casting were performed for analysis.

RESULTS

Pharmacologic delay with preoperative application of topical minoxidil or iloprost was found to have comparable flap viability when compared to surgical delay. Significantly increased viability in all treatment groups was observed when compared with vehicle. Continued postoperative treatment with topical agents had no effect on flap viability. The mechanism of improved flap viability was inducible increases in flap blood volume and perfusion rather than the acute vasodilatory effects of the topical agents or decreased flap hypoxia.

CONCLUSIONS

Preoperative topical application of the vasodilators minoxidil or iloprost improved flap viability comparably to surgical delay. Noninvasive pharmacologic delay may reduce postoperative complications without the need for an additional operation.

CLINICAL RELEVANCE STATEMENT

Preoperative use of topical vasodilators may lead to improved flap viability without the need for a surgical delay procedure. This study may inform future clinical trials examining utility of preoperative topical vasodilators in flap surgery.

Marginal excision of cutaneous mast cell tumors in dogs was not associated with a higher rate of complications or prolonged wound healing than marginal excision of soft tissue sarcomas

OBJECTIVE

To compare wound healing following planned marginal excision of cutaneous mast cell tumors (MCTs) with that of soft tissue sarcomas (STSs) and to identify risk factors for wound healing complications and delay in healing.

ANIMALS

126 dogs that underwent intentional marginal excision of cutaneous MCTs (n = 77) or subcutaneous STSs (49).

PROCEDURES

Medical records of included dogs were reviewed and signalment, tumor size, tumor location, skin closure type, time to healing, reported complications, histopathological grade, and surgical margins were recorded. These variables and outcomes (complication rate and time to complete healing) were compared between dogs in the MCT and STS groups. Potential risk factors for complications and delayed healing were analyzed.

RESULTS

No significant difference between the groups was found in any of the variables. Wound healing complication rates were 29% (22/77) for the MCT group and 31% (15/49) for the STS group. The mean ± SD time to complete healing was 16.5 ± 7.5 days for the MCT group and 17.7 ± 9.3 days for the STS group. These outcomes did not differ significantly between groups. For both groups, the use of subdermal plexus flap reconstruction was associated with the development of complications and increased time to complete healing.

CLINICAL RELEVANCE

Marginal excision of cutaneous MCTs was not associated with a higher rate of complication or prolonged wound healing, compared with marginal excision of STSs. The use of flap reconstruction in skin closure may delay healing and planned adjuvant therapy. Owners should be counseled regarding these risks and where appropriate and feasible, surgery without reconstruction should be considered.

Perivascular Injections of Botulinum Toxin Type A Versus Low Concentration of Ethanol

BACKGROUND

This study aimed to investigate the effect of low concentration ethanol in increasing flap viability by perioperative perivascular application and compared it with that of botulinum toxin type A (BTX-A).

MATERIALS AND METHODS

Twenty-seven Wistar albino rats weighing 300-350 g were used in this study. The subjects were randomly divided into three equal groups: group E (ethanol, n = 9), group B (BTX-A, n = 9), and group S (saline, n = 9). In rats, the dorsal multi-territory perforator flap was elevated, and the agents were injected. In postoperative 1 wk, flap viability and vascular endothelial growth factor levels were evaluated. Also, blood flow, microvascular density, and inflammation degree of both choke zones were assessed.

RESULTS

The mean flap survival area and vascular endothelial growth factor level were significantly higher in group E than in group B and S (P < 0.001). Similarly, blood flow (first choke zone, P < 0.012, and second choke zone, P < 0.001) and microvascular density (first choke zone and second choke zone, P < 0.001) were found to be higher in Group E compared to Group B and S in the evaluation performed from both choke zones. Also, significant inflammation was detected in the ethanol group.

CONCLUSIONS

The positive effects of BTX-A on flap viability were achieved with a low concentration of ethanol. The fact that a low concentration of ethanol increases blood flow, angiogenesis, and flap viability more than BTX-A in the first postoperative week indicates that it can be an alternative agent for perioperative use.

Quantifying the Effect of Topical Nitroglycerin on Random Pattern Flap Perfusion in a Rodent Model: An Application of the ViOptix Intra.Ox for Dynamic Flap Perfusion Assessment and Salvage

BACKGROUND

Near-infrared spectroscopy can detect changes in tissue oxygenation postoperatively that predict flap necrosis. The authors hypothesized that this technology can be applied along with topical nitroglycerin to measure an improvement in tissue oxygenation that correlates with tissue salvage.

METHODS

Dorsal, random pattern flaps measuring 10 × 3 cm were raised using Sprague-Dawley rats. Tissue oxygenation was measured after flap elevation in 10 locations using the ViOptix Intra.Ox. Animals were divided into three groups that received 30 mg of topical nitroglycerin daily, twice-daily, or not at all. Oxygenation measurements were repeated on postoperative day 1 and animals were euthanized on day 7 and evaluated for tissue necrosis.

RESULTS

Tissue necrosis was greatest in controls (51.3 mm) compared to daily (28.8 mm) and twice-daily nitroglycerin (18.8 mm; p = 0.035). Three flap perfusion zones were identified: healthy (proximal, 50 mm), necrotic (distal, 20 mm), and watershed. Immediate postoperative tissue oxygenation was highest in healthy tissue (57.2 percent) and decreased to 33.0 and 19.3 percent in the watershed and necrotic zones, respectively (p < 0.001). One day after treatment with nitroglycerin, oxygenation in the healthy zone did not increase significantly (mean difference, -1.5 percent). The watershed (17.8 percent; p < 0.001) and necrotic zones (16.3 percent; p <0.001) did exhibit significant improvements that were greater than those measured in control tissues (7.9 percent; both p < 0.001).

CONCLUSIONS

Serial perfusion assessment using the ViOptix Intra.Ox measured a significant improvement in flap oxygenation after treatment with topical nitroglycerin. Within the watershed area of the flap, this increase in tissue oxygenation was associated with the salvage of ischemic tissue.

The Use of Botulinum Toxin to Prevent Anastomotic Thrombosis and Promote Flap Survival: A Bridge to Developing Clinical Studies

BACKGROUND

Despite the possibility of using botulinum toxin to improve perfusion and prevent vasospasm, only a few studies have examined the use of botulinum toxin in the setting of flap surgery and thrombosis, and the mechanisms have not been fully explained.

OBJECTIVE

The primary objective of this study was to provide a comprehensive review of the effectiveness of botulinum toxin in anastomotic thrombosis prevention and surgical flap survival to determine the value of conducting large-scale human trials.

METHODS

Using the SYRCLE and CAMRADES criteria, a systematic review was performed. PubMed, Medline, EmBase, and the Cochrane Library were searched for studies that met our eligibility criteria.

RESULTS

Twenty studies were included in the final selection. A total of 397 subjects were included. Eighteen studies used botulinum toxin type A alone, one used botulinum toxin type B alone, and only one used both botulinum toxin type A and botulinum toxin type B. The most commonly used injection technique was a preoperative intradermal injection. The most common procedure performed was a pedicled flap with random pattern skin flaps (65%). The mean injection dose was 28.17 ± 49.21 IU, whereas the mean reported injection time for studies using animal models was 7.4 ± 6.84 days.

CONCLUSIONS

Similar mechanisms demonstrated in animal models may be replicable in humans, allowing botulinum toxin to be used to prolong flap survival. However, many factors, such as optimal injection techniques, dosages, and long-term outcomes of botulinum use in flap surgery, need to be further assessed before applying this to clinical practice.

Effectiveness of Different Surgical Flap Delay Methods and Their Systemic Toxicities

OBJECTIVE

The surgical flap delaying has been shown to be effective in preventing partial flap loss or in preparing larger flaps. However, there is no gold standard flap delay method in the literature. In this study, the authors aimed to compare 3 types of surgical delay methods to determine which model would increase more flap survival. The authors also investigated the effect of delay methods on circulating mononuclear leukocytes as a parameter of DNA damage.

METHODS

Twenty-four Sprague-Dawley male rats were divided into 4 groups. All subjects had a 10 × 3 cm modified McFarlane flap. Surface area measurements, biopsies, and blood samples were taken on the day of sacrification; 7th day for the control group and 14th day for delay groups.

RESULTS

Between incisional surgery delay groups, a significant difference was found in necrosis and apoptosis in the bipedicled group, and only necrosis in the tripedicled group compared to the control. In terms of DNA damage, it was found higher in all experimental groups than in the control group.

CONCLUSIONS

Both incisional surgical delay procedures' results were meaningfully effective when only incisions were made without the elevation of flaps. In conclusion, bipedicled incisional surgical delay seems to be the most effective method in McFarlane experimental flap model whereas two-staged surgeries may increase the risk of systemic toxicity.

Two-Stage Versus One-Stage Nipple-Sparing Mastectomy: Timing of Surgery Prevents Nipple Loss

BACKGROUND

Devascularization of the nipple-areola complex (NAC) before nipple-sparing mastectomy (NSM) enhances blood flow to the skin. This study analyzed the effect of the interval between stages in two-stage (2S) operations and compared the ischemic events with those of one-stage (1S) NSM.

METHODS

Ischemic complications were defined as partial/reversible (PR) or full-thickness/irreversible (FI) skin necrosis of the NAC or flap. The latter encompassed limited areas of the NAC, resulting in loss of nipple height or areolar circumference without affecting the integrity or appearance of the NAC. Outcomes between the two groups were compared using chi-square and both uni- and multivariate analyses.

RESULTS

From 2015 to 2019, 109 breasts underwent 2S NSM and 103 breasts underwent 1S NSM. Grade 2 or 3 breast ptosis was more common in the 2S group than in the 1S group (60.5% vs 30.5%; p < 0.01). The median time between devascularization and NSM was 30 days (range, 11-415 days). After devascularization, ischemic events occurred in 25.7% of the breasts. Nipple loss occurred in 7.8% of the 1S group and 0% of the 2S group. Both PR and FI NAC ischemic events were observed in 66.7% of the breasts when NSM took place fewer than 20 days (n = 9) after devascularization versus 15% when NSM took place 20 days or longer afterward (n = 100). Overall, NAC, flap ischemic complications, or both occurred in 35.9% of the 1S group versus 20.2% of the 2S group (p < 0.05). In the multivariate analysis, the odds ratio of ischemic complications in the 2S versus the 1S group was 0.38 (range, 0.19-0.75).

CONCLUSIONS

Fewer ischemic complications and no nipple loss occurred in 2S NSM. Ischemic events are fewer when the interval between devascularization and NSM is 20 days or longer.

Planned and Unplanned Delayed Anterolateral Thigh Flap Phalloplasty

Background:

Pedicled anterolateral thigh (ALT) flap phalloplasty can be limited by inadequate perfusion. Vascular delay increases perfusion, as delay causes blood vessel formation by limiting the blood supply available to a flap before transfer. We hypothesized that delayed ALT flap phalloplasty would decrease rates of partial flap or phallus loss and other postoperative complications when compared with previously reported complication rates of undelayed single-stage ALT phalloplasty in our practice.

Methods:

A retrospective medical record review was performed on all phalloplasty patients in our practice between January 2016 and September 2019. We found those patients who had completed delayed ALT flap phalloplasty with at least 6 months of delay and 12 months of follow-up. For these patients, we recorded postoperative complications, simultaneous surgeries, subsequent surgeries, and demographic characteristics.

Results:

Five female-to-male transsexuals underwent delayed ALT flap phalloplasty (two were unplanned procedures, three were planned). Planned delay: The average time between Stage 1 and Stage 2 was 6.5 months. Complications for the planned delay cohort were as follows: partial loss of the neophallus not requiring repair (33%), urethral stricture requiring surgical repair (33%). Unplanned delay: The average time between Stage 1 and Stage 2 was 9.1 months. The following complication was seen in the unplanned delay cohort: urethral stricture requiring surgical repair (50%).

Conclusions:

Vascular delay of ALT flap phalloplasty is a successful emergency salvage procedure. Planned delay of ALT flaps provided similar results compared with those previously reported by our practice with standard single-stage approach.

Reconstruction of a large nasal-facial defect using an augmented temporal myocutaneous tube flap in a dog

The muzzle region of dogs contains various composite tissues, which are challenging to recreate during reconstruction. Small or moderate facial/nasal defects can be closed primarily or left for second‐intention healing. However, larger defects require the application of composite tissue or labial advancement flaps. Axial pattern flaps based on the caudal auricular artery, superficial temporal artery (STA), angularis oris artery, and other cutaneous arteries have been reported. In our case, we aim to report the reconstruction of a large composite defect of the rostral and dorsal nasal regions in a dog using an augmented, axial myocutaneous flap based on bilateral STAs. This is a clinical report on a spayed female mixed‐breed dog (age, 7 years; weight, 15 kg), in which a large‐scale nasal–facial composite tissue defect was surgically reconstructed using an axial myocutaneous flap based on bilateral STA branches. A delay technique was applied to prefabricate the flap to enrich the blood supply. New nostrils were created on a folded, rostral hard palate. As a result, the axial tube rotational flap was successfully transferred. The use of delay technique for prefabricating the tube flap optimized its size and survival. In addition to the folded rostral hard palate, the flap fully closed the defects on the face and nose. Functional and cosmetic outcomes were satisfactory, with minimal donor‐site morbidity. In, conclusion, a large‐scale nasal–facial defect in a dog was successfully reconstructed using an augmented tube pedicle flap based on the bilateral STAs, which may, thus, be used to repair very large facial‐nasal defects in dogs.

A large‐scale nasalfacial defect in a dog was successfully reconstructed using an augmented tube pedicle flap based on the bilateral STAs, which may, thus, be used to repair very large facial‐nasal defects in dogs.

Early Experience with External Negative Pressure Delay in Free Anterolateral Thigh Perforator Flap Reconstruction

Negative pressure therapy has been utilized in the treatment of open and closed wounds to increase blood flow and improve wound healing. More recently, external negative pressure has been shown to induce a noninvasive delay phenomenon in animal models by increasing vessel size and density within a planned flap, leading to improvement in flap survival. Although successful in animal models, this new method of delay has not been demonstrated in clinical practice. We present our initial experience with preoperative external negative pressure delay of free anterolateral thigh flaps in upper extremity reconstruction to detail the technique and safety profile of this innovative new technique. External negative pressure delay has the potential to provide results similar to those of traditional surgical delay, while being cost effective, safer, and more convenient for patients. More research is needed to investigate the clinical benefit and cost effectiveness of external negative pressure delay.

Distal Arterialized Venous Supercharging Improves Perfusion and Survival in an Extended Dorsal Three-Perforasome Perforator Flap Rat Model

BACKGROUND

Perforator flaps are commonly applied for a variety of skin defects. Many strategies (e.g., hyperbaric oxygen and preconditioning) have been investigated to improve flap survival, but a postoperative 2.03 to 18.2 percent flap necrosis frequency remains a major complication. The authors hypothesized that a distal arterialized venous supercharged (DAVS) flap procedure might improve perfusion and survival in an extended three-perforasome perforator flap rat model and rescue flap ischemia intraoperatively.

METHODS

One hundred twenty male Sprague-Dawley rats (200 to 300 g) were divided into the thoracodorsal artery (TDA) flap group and the DAVS flap group (n = 60 per group). An approximately 11 × 2.5-cm2 flap based on the TDA perforasome was designed in the TDA flap. A DAVS flap was designed based on the TDA flap and supercharged by anastomosing the rat caudal artery with the deep circumflex iliac vein. At postoperative times 1, 3, 6, and 12 hours and 1, 3, 5, and 7 days, perfusion and angiography were compared. On day 7, flap viability and angiogenesis were assessed using histology and Western blotting.

RESULTS

The DAVS flap showed a higher survival rate compared with the TDA flap (100 percent versus 81.93 ± 5.38 percent; p < 0.001). All blood flow ratios of deep circumflex iliac artery to TDA perforasome and of choke zone II to choke zone I were higher in the DAVS flap (all p < 0.05). Angiography qualitatively revealed that choke vessels in choke zone II dilated earlier and extensively in the DAVS flap group. CD34+ vessels (68.66 ± 12.53/mm2 versus 36.82 ± 8.99/mm2; p < 0.001) and vascular endothelial growth factor protein level (0.22 ± 0.03 versus 0.11 ± 0.03; p < 0.001) were significantly increased in the DAVS flap group.

CONCLUSIONS

The DAVS procedure improves three-perforasome perforator flap survival and can be used for rescuing flap ischemia intraoperatively. Further study is needed before possible clinical adoption for reconstructive operations.

A clinical perspective on adipose-derived cell therapy for enhancing microvascular health and function: Implications and applications for reconstructive surgery

Restoration of form and function requires apposition of tissues in the form of flaps to reconstitute local perfusion. Successful reconstruction relies on flap survival and its integration with the recipient bed. The flap's precariously perfused hypoxic areas undergo adaptive microvascular changes both internally and in connection with the recipient bed. A cell-mediated, coordinated response to hypoxia drives these adaptive processes, restoring a tissue's normoxic homeostasis via de novo vasculogenesis, sprouting angiogenesis, and stabilizing arterialization. As cells exert prolonged and coordinated effects on site, their use as biological agents merit translational consideration of sourcing angio-competent cells and delivering them to territories enduring microcirculatory acclimatization. Angio-competent cells abound in adipose tissue: a reliable, accessible, and expendable source of adipose-derived cells (ADC). When subject to enzymatic digestion and centrifugation, adipose tissue separates its various ADC: A subset of buoyant oil-dense adipocytes (the tissue's parenchymal component) accumulates on a supra-natant layer, whereas the mesenchymal component remains in the infra-natant sediment, containing the tissue's stromal vascular fraction (SVF), where angio-component cells abound. The SVF can be further manipulated, selected, or culture expanded into more specific stromal subsets (herein defined as adipose stromal cells, ASC). While promising clinical applications for ADC await clinical proof and regulatory authorization, basic science investigation is needed to elucidate the specific ADC mechanisms that influence microvascular growth, remodeling, and function following flap surgery. The objective of this article is to share the clinical perspectives of reconstructive plastic surgeons regarding the use of ADC-based therapies to help with flap tissue integration, revascularization, and wound healing. Specifically, the focus will be on considering the potential for ADC as therapeutic agents and how their clinical application motivates basic science opportunities.

Importance of Choke Vessels in Injectable Fillers

Knowledge of facial anatomy is indispensable for dermatologists and plastic surgeons practicing aesthetic medicine, especially for those using fillers, as injection of fillers may be associated with serious complications such as vascular occlusion and blindness. Angiosome and choke vessels play an important role in vascular incidents occurring after filler injections. The objective of this article was to outline the anatomy and pathophysiology of choke vessels, a concept which is not well known to dermatologists.

Irisin pre-treatment promotes multi-territory perforator flap survival in rats: An experimental study

BACKGROUND

The present study was designed to investigate the effects of irisin pre-treatment on multi-territory perforator flap survival and blood vessels of Choke II zone in rats and to explore the underlying mechanism.

METHODS

Eighty adult Sprague-Dawley (SD) rats were divided into the Irisin group and the saline group (N = 40 each), and subjected to multi-territory perforator flap operations on the left flank. Rats in the irisin group were intraperitoneally injected with irisin (40 ng/kg), and rats in the control group were intraperitoneally injected with normal saline. Seven days after operation, we calculated the surviving flap area was calculated, and measured the density of microvessels, epidermal growth factor and blood flow in Choke II zone.

RESULTS

Irisin pre-treatment could improve the flap survival area, increase average density of microvessels and up-regulate the mRNA and protein level of vascular endothelial growth factor, thereby promoting flap angiogenesis.

CONCLUSION

Irisin improved flap blood supply and increase the survival rate of multi-territory perforator flap by promoting angiogenesis of flank multi-territory perforator flap survival in Choke II zone.

Comparison of ischemic preconditioning and BotulinumA Toxin injection for the prevention of ischemia-reperfusion injury in musculocutaneous flaps

Background/aim

The aim of the study was to evaluate the protective effect of Botulinum A toxin injection against ischemia-reperfusion injury.

Materials and methods

Thirty-two Sprague-Dawley rats were divided into: control, ischemia-reperfusion, ischemic preconditioning, and botulinum groups. In all groups the musculocutaneous pedicle flap was occluded for 4 h, and then reperfused to induce ischemia-reperfusion injury. Serum and tissue myeloperoxidase (MPO) and nitric oxide (NO) levels were measured at 24 h and at 10 days.

Results

Tissue MPO levels did not differ significantly between the ischemic preconditioning and botulinum groups at 24 h but was significantly lower in the botulinum group at 10 days. Tissue NO levels were significantly higher in the ischemic preconditioning group compared to the botulinum group at 24 h and at 10 days. Serum MPO showed no significant difference between these two groups at 24 h but was significantly lower in the ischemic preconditioning group compared to the botulinum group at 10 days. Serum NO levels were not significantly different at 24 h but significantly higher in the botulinum group at 10 days.

Conclusion

Findings show that botulinum has a protective effect against the ischemia-reperfusion injury via increased NO and decreased MPO levels in tissue. Based on tissue NO levels, ischemic preconditioning was significantly higher than botulinum.

The effects of optimizing blood inflow in the pedicle on perforator flap survival: A pilot study in a rat model

Background

Perforator flaps have led to a revolution in reconstructive surgery by reducing donor site morbidity. However, many surgeons have witnessed partial flap necrosis. Experimental methods to increase inflow have relied on adding a separate pedicle to the flap. The aim of our study was to experimentally determine whether increasing blood flow in the perforator pedicle itself could benefit flap survival.

Methods

In 30 male Lewis rats, an extended posterior thigh perforator flap was elevated and the pedicle was dissected to its origin from the femoral vessels. The rats were assigned to three groups: control (group I), acute inflow (group II) and arterial preconditioning (group III) depending on the timing of ligation of the femoral artery distal to the site of pedicle emergence. Digital planimetry was performed on postoperative day (POD) 7 and all flaps were monitored using laser Doppler flowmetry perioperatively and postoperatively in three regions (P1-proximal flap, P2-middle of the flap, P3-distal flap).

Results

Digital planimetry showed the highest area of survival in group II (78.12%±8.38%), followed by groups III and I. The laser Doppler results showed statistically significant higher values in group II on POD 7 for P2 and P3. At P3, only group II recorded an increase in the flow on POD 7 in comparison to POD 1.

Conclusions

Optimization of arterial inflow, regardless if performed acutely or as preconditioning, led to increased flap survival in a rat perforator flap model.

Effects of microneedle length and duration of preconditioning on random pattern skin flaps in rats

To date, the surgical delay of skin flaps is the most common and reliable method that increases skin flap survival. In this study, we aimed to increase skin flap viability using preconditioning by microneedling. Seventy-two Sprague Dawley rats were randomly divided into control, surgical flap delay (SFD), and four microneedling groups (7 or 14 days of preconditioning with 0.5 mm or 1 mm needles). Modified McFarlane flaps were raised on the back of rats. In Group I, a caudal pedicled skin flap was raised and the flap survival rate was assessed on postoperative day 14. In the SFD group, a bipedicled flap was created and after 14 days of surgical delay, all skin flaps were raised. In the microneedling groups, 0.5 mm or 1 mm needles were used for 7 or 14 days. The flap survival rates of all microneedling and SFD groups were significantly higher than the control group. The plasma levels of vascular endothelial growth factor (VEGF) did not significantly differ between groups, but the VEGF level of skin samples in the SFD group was higher than the control group. The vessel counts of all microneedling and SFD groups were statistically higher than the control group in all skin samples taken before raising the flaps, but skin samples taken 14 days after raising the skin flap did not show any difference between groups. We showed that preconditioning by microneedling can be used to improve the viability of critical ischemic skin flaps at a level similar to surgical delay.

Make Your Own Deep Inferior Epigastric Artery Perforator Flap: Perforator Delay Improves Deep Inferior Epigastric Artery Perforator Flap Reliability

Abdominal-based autologous breast reconstruction remains a conflict between blood supply and donor site complication. Optimizing esthetics and minimizing recovery and postoperative pain add further complexity. We present a 2-stage technique of deep inferior epigastric artery perforator flap reconstruction to (1) reliably harvest single-vessel flaps while minimizing fat necrosis, (2) decrease abdominal wall morbidity, and (3) improve breast and donor site esthetics.

The prefabricated supraclavicular artery flap in high-risk tracheal stenosis patients

OBJECTIVES/HYPOTHESIS

Primary tracheal resection in appropriately selected patients with tracheal stenosis achieves >90% success rate. Risk factors for complications have been identified, making some patients high risk for this procedure. Herein is a review and discussion of a novel treatment method for tracheal stenosis utilizing a prefabricated composite auricular cartilage graft embedded in a supraclavicular artery island flap (pSCAIF) for tracheal reconstruction in high-risk patients.

STUDY DESIGN

Retrospective case series.

METHODS

After institutional review board approval, cases were analyzed after data collection. Between 2014 and 2016, eight patients underwent airway reconstruction using an auricular cartilage graft prefabricated within a supraclavicular artery island flap reconstruction; all of these were included in the study. Each case was reviewed, and relevant details of patient and disease characteristics, operative course, postoperative course, decannulation, and status at last follow-up were isolated and reported.

RESULTS

Seven of eight patients were female. The most common cause of stenosis was iatrogenically induced multilevel stenosis (7/8 patients). All patients had undergone prior airway procedures, were high risk based on comorbid conditions, and underwent grafting and reconstruction with a composite supraclavicular island flap. All patients continue to follow up in a multidisciplinary clinic, and at last follow-up, eight of eight patients were successfully decannulated.

CONCLUSIONS

The pSCAIF is a novel method for tracheal reconstruction. The analysis of the prefabricated locoregional approach cohort supports its utility for tracheal reconstruction in patients with complicated multilevel stenosis and adverse comorbidities and characteristics.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:641-648, 2020.

Effect of Endogenous Vascular Endothelial Growth Factor on Flap Surgical Delay in a Rat Flap Model

BACKGROUND

Experimental evidence suggests that endogenous vascular endothelial growth factor (VEGF) may play a major role in the surgical delay phenomenon. The purpose of this study was to investigate the effect of endogenous VEGF on flap surgical delay.

METHODS

A total of 82 adult male Sprague-Dawley rats with an average weight of 330 g were used for these experiments. These experiments were then conducted in two parts. In part 1, 32 rats were used to assess the effectiveness of VEGF inhibitor through Western blot assay and enzyme-linked immunosorbent assay. In part 2, 50 rats were used to investigate the effect of VEGF on flap surgical delay by means of arteriography, histologic analysis, and flap viability.

RESULTS

The VEGF protein inhibition ratio reached the maximum (approximately 91.6 percent) in 5 to 7 days. The number of transverse arteries and the number of vessels greater than 0.1 mm in diameter on the 3-day delay duration and the 6-day delay duration were significantly greater than those of the normal group. The number of transverse arteries and the number of vessels greater than 0.1 mm in diameter on the 6-day inhibition duration were not significantly changed compared with the normal group. Microvascular density on the 6-day delay duration obviously increased, whereas the 6-day inhibition duration was not significantly changed in comparison to the normal group.

CONCLUSION

Endogenous VEGF is an initiating factor of the surgical delay effect by controlling choke vessel dilation and neovascularization within the choke zones.

Safe delayed procedure of nipple reconstruction in poorly circulated nipple

Nipple-areolar complex reconstruction represents the final step in breast reconstruction. However, there is no gold standard nipple reconstruction technique that addresses the issue of blood circulation in the flap, which is the most basic complication. Nipple reconstruction was performed in 21 patients. A delayed procedure was performed when a poor outcome was expected due to marginal pinpoint bleeding in the distal tip after flap elevation during nipple reconstruction. The delayed nipple reconstruction can be viewed as a safe and reliable method for improving nipple blood circulation, reducing complications, and enabling long-term nipple projection maintenance in high-risk patients.

Bioactive nanoparticle-based formulations increase survival area of perforator flaps in a rat model

BACKGROUND

Distal flap necrosis is a frequent complication of perforator flaps. Advances in nanotechnology offer exciting new therapeutic approaches. Anti-inflammatory and neo-angiogenic properties of certain metal oxides within the nanoparticles, including bioglass and ceria, may promote flap survival. Here, we explore the ability of various nanoparticle formulations to increase flap survival in a rat model.

MATERIALS AND METHODS

A 9 x 3 cm dorsal flap based on the posterior thigh perforator was raised in 32 Lewis rats. They were divided in 4 groups and treated with different nanoparticle suspensions: I-saline (control), II-Bioglass, III-Bioglass/ceria and IV-Zinc-doped strontium-substituted bioglass/ceria. On post-operative day 7, planimetry and laser Doppler analysis were performed to assess flap survival and various samples were collected to investigate angiogenesis, inflammation and toxicity.

RESULTS

All nanoparticle-treated groups showed a larger flap survival area as compared to the control group (69.9%), with groups IV (77,3%) and II (76%) achieving statistical significance. Blood flow measurements by laser Doppler analysis showed higher perfusion in the nanoparticle-treated flaps. Tissue analysis revealed higher number of blood vessels and increased VEGF expression in groups II and III. The cytokines CD31 and MCP-1 were decreased in groups II and IV.

CONCLUSIONS

Bioglass-based nanoparticles exert local anti-inflammatory and neo-angiogenic effects on the distal part of a perforator flap, increasing therefore its survival. Substitutions in the bioglass matrix and trace metal doping allow for further tuning of regenerative activity. These results showcase the potential utility of these nanoparticles in the clinical setting.

Delayed bipedicled nasolabial flap in facial reconstruction

BACKGROUND

The nasolabial flap is ideal for reconstruction of the nasal alar subunit due to its proximity, color and contour match, and well-placed donor scar. When raised as a random-pattern flap, there is a risk of vascular compromise to the tip with increased flap length and aggressive flap thinning. Surgical delay can greatly improve the chances of tip survival, allowing the harvest of longer flaps with greater reach.

METHODS

We describe our technique of lengthening the nasolabial flap through multiple delay procedures. A bipedicled flap was first raised and then transferred as a unipedicled flap with a 6:1 length-to-width ratio. During the delay process, the flap tip was thinned to the subdermal layer.

RESULTS

In our case series of seven patients, defects as far as the medial canthal area and contralateral ala were reconstructed successfully with no incidence of tip necrosis or flap loss. The resultant flaps were thin enough to be folded over for the reconstruction of alar rim defects.

CONCLUSIONS

We highlight the success of our surgical technique in creating thin and robust nasolabial flaps for the reconstruction of full-thickness defects around the nose.

Flap Basics III: Interpolated Flaps

Paramedian forehead and melolabial flaps are the most common examples of interpolated flaps used by facial plastic surgeons and are excellent options for reconstruction of the midface after Mohs surgery. They provide superior tissue match in terms of thickness, texture, and color, while leaving minimal defects at the tissue donor sites. The main advantage of interpolated flaps is the robust blood supply, which can be either axial of randomly based, and the maintenance of the integrity of facial landmarks. The main disadvantage is the frequent need for a multistage procedure, which eliminates some patients from consideration.

The Delay Phenomenon: Is One Surgical Delay Technique Superior?

Background:

Surgical delay remains a common method for improving flap survival. However, the optimal surgical technique has not been determined. In this article, we compare flap perfusion, viable surface area, and flap contraction of 2 surgical delay techniques.

Methods:

Male Sprague-Dawley rats were divided into 3 groups. In the incisional surgical delay group (n = 9), a 9 × 3 cm dorsal flap was incised on 3 sides without undermining, leaving a cranial pedicle. In the bipedicle surgical delay group (BSD, n = 9), a 9 × 3 cm dorsal flap was incised laterally and undermined, leaving cranial and caudal pedicles. Control group (n = 16) animals did not undergo a delay procedure. Ten days following surgical delay, all flaps for all groups were raised, leaving a cranial pedicle. A silicone sheet separated the flap and the wound bed. On postoperative day (POD) 7, viable surface area was determined clinically. Contraction compared to POD 0 was measured with ImageJ software. Perfusion was measured with Laser Doppler Imaging. The Kruskal-Wallis with Dunn’s multiple comparisons test was performed for group comparisons.

Results:

BSD preserved significantly more viable surface area on POD 7 (13.7 ± 4.5 cm²) than Control (8.7 ± 1.8 cm²; P = 0.01). BSD also showed significantly less contraction (21.0% ± 13.5%) than Control (45.9% ± 19.7%; P = 0.0045). BSD and incisional surgical delay showed significantly increased perfusion compared with Control on POD 0 (P = 0.02 and 0.049, respectively), which persisted on POD 3. This trend resolved by POD 7.

Conclusion:

BSD showed improved early perfusion, increased viable surface area, and reduced contraction compared to control, suggesting that BSD is the superior flap design for preclinical modeling.

Detrimental effect of Hypoxia-inducible factor-1α-induced autophagy on multiterritory perforator flap survival in rats

Hypoxia-inducible factor-1α (HIF-1α) plays a key role in angiogenesis, improves flap survival, and activates autophagy. The effect of HIF-1α-induced autophagy is still debatable. Thus, we investigated the effect of HIF-1α-induced autophagy on multiterritory perforator flap survival. In this study, 99 male Sprague-Dawley rats received multiterritory perforator flap procedure and were divided into three groups with 33 each. The dimethyloxalylglycine (DMOG) plus 3-methyladenine (3-MA) group received intraperitoneal injection of DMOG (40 mg/kg) and 3-MA (10 mg/kg). The DMOG group and control group received comparative DMOG and saline respectively. On postoperative day (POD) 7, HIF-1α’s activities of flap survival and perfusion improvement were confirmed in DMOG group, however, its positive effects were further enhanced by co-administration of autophagy inhibitor, 3-MA. On POD 1, vascular endothelial growth factor, mean microvascular density and blood perfusion were not affected by HIF-1α up-regulation or autophagy inactivation. However, HIF-1α-induced autophagy augments apoptosis and oxidative stress. The increased level of apoptosis and oxidative stress was reversed by 3-MA and resulted in further flap survival improvement. In conclusion, HIF-1α-induced autophagy has a detrimental effect on multiterritory perforator flap survival and the flap survival was determined by the combined effects of ischemia and reperfusion injury.

Inflammatory response associated with choke vessel remodeling in the extended perforator flap model

Ischemic necrosis of the surgical flap is a common complication. The behavior of choke vessels has an important role in skin flap survival. However, the mechanism of choke vessel remodeling has remained elusive. The purpose of the present study was to investigate the possible association between inflammatory responses and choke vessel remodeling in the extended perforator flap model in rats. After flap elevation, the animals were randomly divided into three groups (n=6 in each) for tissue analysis at three, five or seven days after flap surgery. Six additional rats served as a control group (no flap elevation). Tissue samples were collected from the choke zone for histological, western blot and PCR analyses. Monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-α (TNF-α) as inflammatory cytokines were examined in the present study. Histopathological analysis showed that dilation of choke vessels and increased vessel wall thickness was obvious after flap elevation. It also showed edema, inflammation cell aggregation after the operation. Compared with the control group, the protein and mRNA expression levels of MCP-1 and TNF-α were significantly increased at days 3, 5 and 7 after flap elevation, while reaching a maximum at day 5. These findings indicated that inflammatory responses may have an important role in choke vessel remodeling. MCP-1 and TNF-α may be considered as potential targets for modulating the behavior of choke vessels.

Prefabrication and free transfer of a tissue engineered composite flap - An experimental model in the rat

BACKGROUND

The technique of flap-prefabrication has been successfully established in tissue engineering: missing intrinsic vascularisation of engineered tissue can be generated in vivo by microsurgical vesselloop construction. It is possible to move engineered tissue into a defect with microsurgery. In the literature, the combination of engineered tissue covered with skin is not widely reported.

OBJECTIVE

Aim of this study was to establish a model to investigate scaffold prefabrication with full thickness skin graft coverage with subsequent free tissue transfer.

METHODS

8 Wistar rats were operated in 2 separate steps: 1) after creating an arteriovenous loop with the femoral vessels, a porous scaffold was placed on the loop and covered with an inguinally based skin flap. A control was implanted without loop into the contralateral groin. 2) 6 weeks later the prefabricated composite flaps were microsurgically transferred to the cervical region. Skin-island monitoring was performed with Laser Doppler-scanner after the transfer.

RESULTS

Continuous loss of the skin islands was observed within 72 hours. Complications included wound-dehiscence, thrombosis and death from anaesthesia; in spite of consistent loop viability.

CONCLUSION

Evaluation showed that modifications are necessary to maintain the skin-island cove.

Efficacy of Liposuction as a Delay Method for Improving Flap Survival

BACKGROUND

Flaps are often used in repairing tissue defects and partial or full flap loss is still an important morbidity cause. Several techniques have been tried to increase flap circulation but none of these could replace the delay technique. Our goal in this study is to show the efficacy of liposuction in delay of dorsal rat cutaneous flaps and improvement in flap survival.

METHODS

Twenty-four Wistar rats were used. The rats in group 1 received 9 × 3-sized caudally-based random pattern skin flaps. In group 2, liposuction was done under the tissue island spotted as the flap and after 14 days, standard flap surgery was done. In group 3, surgical delay was done and after 14 days, standard flap surgery was done. In group 4, liposuction was done under the tissue island spotted as the flap and standard flap surgery was done right after the liposuction.

RESULTS

The rate of necrotic tissue in group 3 (surgical delay; mean % 13.7) was less than the rate in group 2 (liposuction delay; mean % 15.1), although the difference was not statistically significant. The necrosis rates in group 3 (surgical delay) and group 2 (liposuction delay) were less than the rates in both group 1 (only flap; mean % 41.5) and group 4 (liposuction flap; mean % 40.0) and this difference was statistically significant (p < 0.0001).

CONCLUSION

Liposuction can be an alternative to surgical delay as a less invasive method in the clinic.

NO LEVEL ASSIGNED

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .