Perforator-based flap in rats: a new experimental model

Teaching of Microsurgery and Supermicrosurgery for Residents

On the basis of our numerous years of experience in teaching residents without microsurgery experience and assisting in the initiation of microsurgery in clinical practice, we herein describe the general procedures and crucial aspects to consider regarding microsurgery and supermicrosurgery training for residents. The description focuses on training methods, surgical skills, and training time and effort. The target audience of the training is residents who have never performed microsurgery. We believe that any person, regardless of operative experience, can acquire the technique for microsurgery and supermicrosurgery by performing 4 to 5 hours of training per day over a total of 30 days within this program setting. Considering individual differences in learning and experience, the training can be completed in a shorter period by performing additional daily training. It is relatively simple for a well-trained microsurgeon to master the uncommon supermicrosurgery techniques. We hope that this report will help as many residents as possible in learning the art of (super)microsurgery.

Rat Perforator and Skin Vessels Vascular Mapping: An Original Anatomical Study About 140 Vessels and Literature Review

INTRODUCTION

Recent microsurgical reconstruction techniques benefit from the use of skin and perforator flaps that spare the donor sites. Studies on these skin flaps in rat models are numerous but there is currently no reference regarding the position of the perforators, their caliber, and the length of the vascular pedicles.

METHODS

We performed an anatomical study on 10 Wistar rats and 140 vessels: cranial epigastric (CE), superficial inferior epigastric (SIE), lateral thoracic (LT), posterior thigh (PT), deep iliac circumflex (DCI) and posterior intercostal (PIC) vessels. The evaluation criteria were the external caliber, the length of the pedicle, and the position of the vessels reported on the skin surface.

RESULTS

Data from the six perforator vascular pedicles are reported, with figures illustrating the orthonormal reference frame, the representation of the vessel's position, the cloud of points corresponding to the various measurements, and the average representation of the collected data. The analysis of the literature does not find similar studies; the different vascular pedicles are discussed as well as the limitations of our study: evaluation of cadaver specimen, presence of the very mobile panniculus carnosus, other perforator vessels not evaluated as well as the precise definition of perforating vessels.

CONCLUSIONS

Our work describes the vascular calibers, pedicle lengths, and location of birth and arrival at the skin of the perforator vessels PT, DCI, PIC, LT, SIE, and CE in rat animal models. This work, without an equivalent in the literature, lays the foundation for future studies about flap perfusion, microsurgery, and super microsurgery learning.

MiR-590-3p affects the function of adipose-derived stem cells (ADSCs) on the survival of skin flaps by targeting VEGFA

Introduction

Partial necrosis of skin flaps is still a substantial problem in plastic and reconstructive surgery. In this study, the role of miR-590-3p in adipose-derived stem cells (ADSCs) transplantation in improving the survival of skin flap in a mouse model was delved into.

Method

An abdominal perforator flap model was established in mice. The histopathological examination of mice skin tissues after ADSCs transplantation was implemented using Hematoxylin & eosin (H&E) staining. Immunohistochemistry (IHC) or immunofluorescence (IF) staining was utilized to assess the PCNA or CD31 levels. The concentrations of VEGFA in the culture medium were quantified using a VEGFA ELISA kit.

Result

The damage of tissue in the skin flap was dramatically relieved by ADSCs transplantation. MiR-590-3p overexpression notably suppressed, while miR-590-3p knockdown facilitated skin flap survival by regulating PCNA, VCAM-1, and VEGFA levels. MiR-590-3p targeted VEGFA to regulate its expression. The knockdown of VEGFA significantly inhibited, while overexpression of VEGFA notably promoted the survival of skin flap.

Conclusion

ADSCs transplantation promotes skin flap survival by boosting angiogenesis. The miR-590-3p/VEGFA axis modulates skin flap angiogenesis and survival in ADSCs. These results reveal that interfering with miR-590-3p in ADSCs could potentially be a novel therapeutic target for the improvement of skin flap survival.

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ADSCs transplantation improve perforator flap survival.

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Agomir-590-3p transfected ADSCs inhibited perforator flap survival.

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MiR-590-3p targeted VEGFA 3′UTR to regulate its expression.

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The miR-590-3p/VEGFA axis in ADSCs modulates skin flap angiogenesis.

Melatonin Improved the Survival of Multi-Territory Perforator Flaps by Promoting Angiogenesis and Inhibiting Apoptosis via the NRF2/FUNDC1 Axis

Background: Multi-territory perforator flaps are a reconstructive measure for repairing large soft tissue defects caused by tumors or trauma. However, the use of these flaps in clinical practice has been restricted due to the uncertain blood supply. Therefore, promoting the survival of the multi-territory perforator flap is critical for clinical repair and reconstruction. In our study, we explored the effects of melatonin (MLT) on multi-territory perforator flaps and the possible molecular mechanisms.

Materials and Methods: Seventy-two Sprague–Dawley rats (250–300 g) were randomly divided into 3 groups (n = 24): Control, MLT and MLT + ML385 groups. First, we assessed the survival area of the flap, followed by the micro-vessel density and CD31-positive vessel expression. Apoptosis of the skin flap under immunofluorescence and expression of the apoptosis-related proteins Bcl-2, Bax and Caspase3 were measured. Additionally, angiogenesis of the skin flaps was shown by angiography, and NRF2 and FUNDC1 mRNA and protein expression was detected by real-time PCR and western blotting.

Results: The results showed that MLT increased the survival area of the multi-territory perforator flap, which was related to increased angiogenesis and decreased apoptosis. We also found that mRNA and protein of NRF2 and FUNDC1 levels were significantly increased after MLT treatment, and an NRF2 inhibitor reversed the ability of MLT to enhance multi-territory perforator flap survival, promote angiogenesis and inhibit apoptosis and reduced FUNDC1 protein expression.

Conclusion: MLT promoted angiogenesis and inhibited apoptosis to promote the survival of multi-territory perforator flaps, which may be regulated via the NRF2/FUNDC1 axis.

TULUA: Effects of Flap Undermining and Type of Wall Plicature in a Rat Model Abdominoplasty

BACKGROUND

TULUA, a transverse plication lipoabdominoplasty, which excludes elevation of the supraumbilical flap and includes a skin graft neoumbilicoplasty, claims greater safety and better results. An animal study was designed to compare it, with two current techniques.

MATERIALS AND METHODS

Three matched groups of 12 rats had combined liposuction and abdominoplasty. Liposuction was extensive and unrestricted. Groups 1 and 2 had vertical plication and transposition umbilicoplasty, and group 3 had transverse plication and neoumbilicoplasty. Flap elevation in the epigastrium was wide to costal margins in group 1, limited to a tunnel in group 2, and no dissection in group 3. The animals were observed for 21 days and then euthanized. Intraoperative, postoperative, and postmortem variables and findings were measured and analyzed to find differences between groups.

RESULTS

Transverse lipoabdominoplasty demonstrated a wider wall plication area, as well as a decrease in tension to close the wound, causing the horizontal scar to remain in a low position. In vertical plication lipoabdominoplasty groups, flap necrosis and seromas were more frequent, and the umbilical position descended due to secondary healing and scar contraction. The scar's scores were better in the transverse group and were confirmed when evaluated by external observers.In postmortem examination, horizontal plication presented less widening; perforator vessels were preserved when surgical undermining of the upper abdomen was not performed, and there were fewer seromas.

CONCLUSION

In a rat model, TULUA demonstrates superior results and a decrease in complications when compared to lipoabdominoplasties with vertical plication and wide or tunneled dissection in the upper abdomen.

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 .

Improvement of multiterritory perforator flap survival supported by a hybrid perfusion mode: A novel strategy and literature review

Perforator flaps have been widely used in clinical Settings, however, unexpected necrosis was still commonly encountered in the distal portions of multiterritory flaps known as Choke zone III. In this study, we introduced a novel hybrid perfusion technique which is different from the established one of arterial supercharging or venous superdrainage to improve multiterritory flap survival with success. In order to ensure the entire flap survival of multiterritory flaps extending to choke zone III, a "hybrid perfusion" mode by anastomosing a distal vein of the flap with a recipient artery was carried out in two cases based on our previous basic study. In addition, a systematic literature review regarding the established microsurgical assistant techniques of arterial supercharging and venous superdrainage techniques were performed. Both flaps survived uneventfully. At a minimal follow-up of six months, both patients were satisfied with the results. This novel hybrid perfusion technique provides a simple new concept in solving partial necrosis of multiterritory flaps. Further practice is guaranteed for better understanding this unconventional attempt.

Effect of short-term ischemia on microcirculation and wound healing of adipocutaneous flaps in the rat

PURPOSE

Composite flaps used in reconstructive surgery may intra- and postoperatively suffer from hypoperfusion and/or ischemia-reperfusion influencing wound healing. We aimed to follow-up the effect of ischemia on adipocutaneous flaps' wound healing and microcirculation.

METHODS

In anesthetized rats groin flaps were formed bilaterally. In Control group the flaps were repositioned and sutured back. In Ischemia-Reperfusion (I/R) group before repositioning and suturing the flap pedicles were clamped for 60 minutes. Laser Doppler (LD) fluxmetry and temperature probes were applied on the cranial, central and caudal flap regions before/after preparation and ischemia, re-suturing, and on the 1st-3rd-5th-7th-14th postoperative days, before the final examinations and biopsies for histology.

RESULTS

Flaps' skin temperature quickly recovered after repositioning. LD values were lower in the I/R group, reaching a significant level by the 3rd postoperative day, and remained lowered till the 14th day. The magnitude of alterations differed in the flap regions. Histologically normal wound healing process was seen, except for some I/R flaps, where hypertrophized mammary glands were found.

CONCLUSIONS

Short-term ischemia could influence flap microcirculation and wound healing, and may result in hypertrophized mammary glands. Laser Doppler could be used to evaluate intra- and postoperative microcirculatory changes and may have significance in predicting complications.

The feasibility and survival mechanism of a large free flap supported by a novel hybrid perfusion mode

OBJECTIVES

In this study, we presented a novel hybrid perfusion mode in an attempt to provide a new strategy to improve the survival of an extended large flap and discuss its possible mechanisms.

MATERIALS AND METHODS

A 14 × 10 cm flap was designed on the rabbit abdomen. Ninety-six rabbits were randomly divided into three groups based on the flap perfusion mode: control group I (CON 1, physiological perfusion mode with bilateral deep inferior epigastric vascular pedicles intact), control group II (CON 2, physiological perfusion mode with single deep inferior epigastric vascular pedicle intact), hybrid nourished group (physiological perfusion as in CON 2 combined with arterialized venous nonphysiological perfusion mode, referred to as a hybrid perfusion mode). Flap survival, status of vascular perfusion, microvasculature, histopathology, expression of CD34, eNOs, VEGF and metabolic status of the flaps by LC-MS were assessed in each group.

RESULTS

The results of "hybrid nourished" flaps were similar to the traditional flaps in terms of flap survival, level of vascular perfusion and microvasculature except the status of metabolites.

CONCLUSIONS

The feasibility of this novel hybrid perfusion mode will greatly extend the indications of flap transfer and efficiently improve the survival reliability of large flaps. In a sense, this mode will be an ideological emancipation for the field of flap surgery.

Blood Supply to the Integument of the Abdomen of the Rat: A Surgical Perspective

BACKGROUND

Many fundamental questions regarding the blood supply to the integument of the rat remain to be clarified, namely the degree of homology between rat and humans. The aim of this work was to characterize in detail the macro and microvascular blood supply to the integument covering the ventrolateral aspect of the abdominal wall of the rat.

METHODS

Two hundred five Wistar male rats weighing 250-350 g were used. They were submitted to gross anatomical dissection after intravascular colored latex injection (n = 30); conversion in modified Spalteholz cleared specimens (n=10); intravascular injection of a Perspex solution, and then corroded, in order to produce vascular corrosion casts of the vessels in the region (n = 5); histological studies (n = 20); scanning electron microscopy of vascular corrosion casts (n = 10); surgical dissection of the superficial caudal epigastric vessels (n = 100); and to thermographic evaluation (n = 30).

RESULTS

The ventrolateral abdominal wall presented a dominant superficial vascular system, which was composed mainly of branches from the superficial caudal epigastric artery and vein in the caudal half. The cranial half still received significant arterial contributions from the lateral thoracic artery in all cases and from large perforators coming from the intercostal arteries and from the deep cranial epigastric artery.

CONCLUSIONS

These data show that rats and humans present a great deal of homology regarding the blood supply to the ventrolateral aspect of the abdominal integument. However, there are also significant differences that must be taken into consideration when performing and interpreting experimental procedures in rats.

What's the remedy for the distal necrosis of DIEP flap, better venous drain or more arterial supply?

Background

We developed a novel pedicled DIEP flap model in rat to explore the possible remedy for the distal necrosis of the flap.

Methods

A deep inferior epigastric perforator (DIEP) flap, based on the second right cranial perforator (P2) as the main pedicle, was elevated in 48 Sprague-Dawley rats. The rats were randomized into 4 groups: group I, the left P2 remaining intact as supercharging; group II, the left P2 artery alone kept as supercharging; group III, the left P2 vein alone kept as supercharging; group IV, no supercharging. Transcutaneous oxygen pressure (TcPO₂) and transcutaneous carbon dioxide pressure (TcPCO₂) were measured immediately after flap elevation, protein level of Hif-1a was measured 48 hours later, and flap survival was assessed 7 days postoperatively.

Results

Blockade of artery led to significantly lower TcPO₂, higher TcPCO₂, and higher expression level of Hif-1a in the distal side of the flap in group III and group IV, than those of group I and group II. At 7 days post surgery, significantly lower flap survival rates were observed in group III (81.9 ± 5.7%) and group IV (78.4 ± 6.5%), compared to observed in group I (97.2 ± 3.0%) and group II (94.2 ± 6.2%).

Conclusions

It might be arterial insufficiency, not venous congestion, which mainly caused the distal necrosis of the DIEP flap in rat. Arterial instead of venous supercharging might be a more effective procedure that improves circulation to zone IV of the flap.

Saphenous artery-based flap models in rats: new flap designs for experimental studies

BACKGROUND

Experimental research using laboratory animals provides substantial data about reconstructive surgery. However, the literature does not include any experimental studies that have used flap models on the hind limbs of rats. To gain an understanding of the physiology of lower-extremity flaps and of flap failures, this study assessed the cutaneous perforators of the saphenous artery, and new flap models were designed for the hind limbs of rats.

MATERIALS AND METHODS

The experiment was designed to include three stages and used 35 rats. The first stage involved mapping the perforators of the saphenous artery. In the second stage, the contents and structures of McFarlane, epigastric, and anterior hind limb flap tissues were compared histologically. The third stage of the study involved designing and comparing different flaps for the hind limbs of the rats and included random flaps, perforator-based peninsular flaps, perforator-based island flaps, and perforator-based flaps with rotated pedicles. Postoperative necrosis ratios were evaluated using computer-based software.

RESULTS

Mapping of the saphenous artery perforators revealed an average of 2.2 septocutaneous arteries in each hind limb. Histologic studies showed thick dermis and panniculus carnosus in the McFarlane flaps, thick dermis, and thin panniculus carnosus layers in the epigastric flaps, and thin subcutaneous tissue with no panniculus carnosus tissue in the skin of the hind limbs. The results of the flap studies that used random flaps showed a 52.4% necrosis, while there was no necrosis when perforator-based peninsular flaps, island flaps, and flaps with rotated pedicles were used.

CONCLUSIONS

New flap models used on the saphenous artery perforators of the hind limbs of rats can provide valuable information about the physiology of lower-extremity flaps. New studies can also be designed based on these flap models to acquire more knowledge about pathologic conditions such as ischemia and venous insufficiency.

Impact of different antithrombotics on the microcirculation and viability of perforator-based ischaemic skin flaps in a small animal model

The effects of antithrombotic drugs on random and free flap survival have been investigated in the past, but the experimental and clinical results are not in agreement. A perforator-based critical ischaemia model was used to evaluate the effects of different perioperatively administered pharmaceutical agents on tissue ischaemia and to assess the potential additional haemorheological or vasodilative effects of antithrombotics on flap microcirculation. Combined laser Doppler flowmetry and remission spectroscopy revealed an increase in certain microcirculation parameters in most groups in comparison with saline controls, and these changes correlated with flap survival. Clopidogrel and hirudin significantly improved the amount of viable flap tissue in comparison with controls, while unfractioned heparin had a negative effect on flap survival. Low molecular weight heparin, aspirin, pentoxifylline, and hydroxyethyl starch had no impact on the amount of viable flap tissue. A higher complication rate was observed in all experimental groups, but only clopidogrel had a negative impact on the flap viability. Our results add to the body of evidence supporting the conclusion that perioperative antithrombotic treatment improves flap survival. Clopidogrel and hirudin are effective pharmacological agents that significantly increased the viability of perforator-based skin flaps in rats, but at a higher risk of postoperative bleeding.

A Novel Perforator Flap Training Model Using a Chicken Leg

INTRODUCTION

Living animal models are frequently used for perforator flap dissection training, but no ex vivo models have been described. The aim of this study is to present a novel nonliving model for perforator flap training based on a constant perforator in the chicken leg.

METHODS

A total of 15 chicken legs were used in this study. Anatomical dissection of the perforator was performed after its identification using ink injection, and in four of these specimens a perforator-based flap was raised.

RESULTS

The anatomical dissection revealed a constant intramuscular perforator with a median length of 5.7 cm. Median proximal and distal vessel diameters were 0.93 and 0.4 mm, respectively. The median dissection time was 77.5 minutes.

CONCLUSION

This study introduces a novel, affordable, and reproducible model for the intramuscular dissection of a perforator-based flap using an ex vivo animal model. Its consistent perforator and appropriate-sized vessels make it useful for training.

Lateral thoracic artery perforator-based flap: a new experimental model

BACKGROUND

The aim of this study was to describe a new experimental perforator-based flap in rats, supplied by lateral thoracic artery perforator.

METHODS

Through out the study, two control and two experimental groups were created consisting of six rats in each group. In the first control group (group 1), mid-axillary line and the fourth intercostal space intersection were used as the center of the flap. A 3 × 2 cm flap was designed and elevated above the cutaneous maximus muscle by transecting all connections with the muscle. In the second control group (group 2), the flap was extended caudally, and 3 × 6 cm flap was designed. Then, the flap was elevated in the same manner as it was described for group 1. In the first experimental group (group 3) 3 × 2 cm flap and in the second experimental group (group 4) 3 × 6 cm flap were designed like control groups. The flaps were islanded on a single musculocutan perforator arising from lateral thoracic artery. The surviving skin paddle areas were calculated on postoperative day 7.

RESULTS

The flap viability was calculated 0% for control groups (groups 1 and 2), 100% for the first experimental group (group 3), between 33.3% and 37.7% for the second experimental group (group 4; mean ± standard deviation, 34.76% ± 1.92%).

CONCLUSIONS

This new lateral thoracic artery perforator-based flap has a constant anatomy and reliable survival pattern. Also, easy harvesting and the possibility of designing two flaps per animal make this new flap an appealing model for pathophysiological or pharmacologic researches.

Bilirubin provides perforator flap protection from ischaemia-reperfusion injury in a rat model: a preliminary result

The use of bilirubin, a well-known and powerful antioxidant, has gained popularity in recent years because of its role in the prevention of ischaemic heart disease in patients with Gilbert's syndrome. We investigate the effects of bilirubin on ischaemia-reperfusion (I/R) injury using a rat perforator flap model. Forty-eight rats were randomly divided into two groups: experimental (bilirubin) group (n = 24) and control group (n = 24). In each group, elevated bilateral deep inferior epigastric perforator (DIEP) flaps were created. The right (no ischaemia side) and left (ischaemia side) DIEP flaps were separated according to the presence of ischaemia induction. Ischaemia was induced in anaesthetised rats by perforator clamping for 15 or 30 minutes. After surgery, the flap survival was assessed daily on postoperative days 0 to 5, and overall histological changes of DIEP flaps above the perforator were analysed at postoperative day 5. The flap survival rate in the bilirubin group was significantly higher than that in the control group at the ischaemia side following perforator clamping for 15 or 30 minutes (93·42 ± 4·48% versus 89·63 ± 3·98%, P = 0·002; and 83·96 ± 4·23% versus 36·46 ± 6·38%, P < 0·001, respectively). The difference in flap survival between the two groups was the most prominent on the ischaemic side following 30 minutes of perforator clamping. From a morphologic perspective, pre-treatment with bilirubin was found to alleviate perforator flap necrosis caused by I/R injury in this experimental rat model.

Comparisons of the postoperative rectus abdominis muscle thickness and the biomechanical properties of donor sites among different subtypes of muscle-sparing transverse rectus abdominis myocutaneous flaps (MS0, MS1, MS2, MS3): a rat model

BACKGROUND

The primary presumed advantages of the deep inferior epigastric perforator flap over the other muscle-sparing (MS) transverse rectus abdominis myocutaneous flaps are the improved functional rectus abdominis muscle outcomes and decreased abdominal contour morbidities. The purpose of this study was to verify this viewpoint objectively and quantitatively using an animal model.

METHODS

Six rats were used in the pilot study and 40 rats were equally divided into a control group and 4 experimental groups (MS0, MS1, MS2, and MS3) according to the amount of rectus abdominis muscles harvested. At 3 and 6 weeks, 4 rats in each group were killed, then, the percentage of residual rectus abdominis muscle thickness compared with the control side and the ultimate load at failure of the abdominal wall were recorded and compared.

RESULTS

All of the flaps survived completely without complications. Regarding the percentage of residual rectus abdominis muscle thickness compared with the control side, the results suggested MS3 > MS2 ≈ MS1 > MS0; concerning the ultimate load at failure of the abdominal wall, the results showed MS3 ≈ MS2 > MS1 > MS0. (≈: P > 0.05; >: P < 0.05).

CONCLUSIONS

According to the findings of this study, we advocate the use of the deep inferior epigastric perforator flap when possible, and the MS2-transverse rectus abdominis myocutaneous flap can serve as a backup when the perforator anatomy does not meet the flap safety criteria for preservation of rectus abdominis muscle function.

Comparison of two different vascular delay methods in a rat cranial epigastric perforator flap model

The effectiveness of vascular delay in transverse rectus abdominis muscle flaps has been demonstrated in many studies. In deep inferior epigastric perforator flaps, however, the effectiveness of ligation of deep versus superficial epigastric vessels in producing delay is unclear. Using a rat model, we compared ligation of deep and superficial vessels with each other and with a (nondelayed) control group (n = 10). One vascular delay group (n = 10) had ligation of the contralateral cranial epigastric vessels (homolog to the human deep inferior epigastric vessels); the other (n = 10) had ligation of contralateral superficial inferior epigastric vessels. One week later, cranial epigastric perforator flap elevation was performed. Both vascular techniques were effective in producing delay, and there was no statistically significant difference between the 2 groups. Ligation of superficial inferior epigastric vessels, deep inferior epigastric vessels, or both, at least 1 week prior to the deep inferior epigastric perforator flap elevation may increase the usable skin paddle area in humans.

Microcirculation in single and multiple-based perforator flaps in an experimental model of rats

Our aim was to evaluate the effect of single and multiple-based perforator flaps on the microcirculation in rats. Two symmetrical abdominal flaps were raised around the midline in 17 rats, and sutured into their original positions after dissection. All major perforators in the flap were left intact on one side, and on the opposite side only one perforator was retained. The microcirculation in the flaps was measured with laser Doppler perfusion imaging at different time intervals. Before dissection of the flap the mean (SD) microcirculation was 5.5 (1.6) units in the multiple-based perforator flap and 5.5 (1.4) in the single-based perforator flap. Within the first two hours after the flap had been raised the highest microcirculation was found after 30 minutes with 7.3 (1.3) units in the multiple-based perforator flap compared with 6.5 (1.4) units in the single-based perforator flap (p = 0.002). We conclude that the microcirculation in the single-based perforator flap was not reduced after dissection. However, a reactive hyperaemic response was found only in the multiple-based perforator flap.

Skin viability and wound strength in single and multiple based perforator flaps in an experimental rat model

Our aim was to evaluate the effect of single and multiple based perforator flaps on the skin viability and wound strength in rats. We used 17 Wistar rats in which two symmetrical abdominal flaps were raised around the midline. On one side all major perforators to the flap were left intact, and on the other side only one perforator was retained. After dissection, the flaps were sutured back in their original position. After seven days each rat was killed and the skin viability and wound strength were measured. The multiple based perforator flap had a mean skin viability of 98% compared with 95% in the single based perforator flap (p =0.08). The mean (SD) wound strength was 3.8 (0.9) N in the multiple based perforator flap compared with 3.0 (1.1) N in the single based perforator flap (p =0.02). We conclude that there is significantly greater wound strength at day 7 with the multiple based perforator flap than with the single one.

Effects of venous supercharging in deep inferior epigastric artery perforator flap

PURPOSE: To evaluate the effects of venous supercharging in deep inferior epigastric artery perforator flap in rats. METHODS: 20 Wistar rats were randomized in 2 groups: control group (C), all had flaps raised based on the deep inferior epigastric perforator vessels (DIEP), and experimental group (E), which was identical to group C, except that the contralateral superficial inferior epigastric vein was also kept with the flap. Flow studies using laser Doppler flowmetry where performed daily in the four zones of the flap. On the 7th postoperative day rats were killed and flap survival was determined using digital planimetry. RESULTS: Flow values were presented as a percentage of the baseline flow after incision of the flap edges. The surviving flap area was demonstrated as a percentage of the total flap area. Evaluation by digital planimetry showed that flap survival in group E was higher than in group C (97,38%±1,32%vs.44,13%±4,83%, p=0,0006). CONCLUSION: This study shows that venous supercharging of the rat DIEP flap results in greater flap survival.

Cutaneous Viability in a Rat Pedicled TRAM Flap Model

BACKGROUND

The transverse rectus abdominis musculocutaneous (TRAM) flap is widely used in breast reconstruction. However, morbidity with its pedicled form has resulted in a high incidence of complications. The authors conducted a study of the pedicled TRAM flap procedure in 35 female Wistar rats based on the left deep inferior epigastric vessel, which was nondominant.

METHODS

In all the rats, the flap was divided into four areas: area 1, the skin on the left rectus abdominis muscle pedicle; area 2, the skin contralateral to the midline, opposite of the left rectus abdominis muscle pedicle; and areas 3 and 4, the skin lateral to areas 1 and 2, respectively. The occurrence, percentage, and distribution of necrosis on the TRAM flap surface were determined.

RESULTS

Necrosis was observed at four statistically distinct and significant levels, distributed in the four different areas as follows: area 1, 9 percent; area 2, 37 percent; area 3, 74 percent; and area 4, 100 percent (p < 0.001). The median proportion of necrosed flap surface was 15 percent (range, 2 to 42 percent).

CONCLUSIONS

The determination of necrosis allowed us to identify three distinct levels of necrosis: area 4 with the highest scores, area 3 with intermediate scores, and areas 1 and 2 with the lowest scores (p < 0.001). Areas 1 and 2 of the TRAM flap surface had less incidence of necrosis, contrary to the lateral areas 3 and 4, in which cutaneous necrosis was found to be more significant.

Perforator-Sparing Abdominoplasty Technique in the Presence of Bilateral Subcostal Scars after Gastric Bypass

BACKGROUND

The number of patients after gastric bypass being referred to plastic surgery units for secondary plastic surgery procedures is increasing. The characteristic abdominal deformity includes a draping apron of panniculus, occasionally associated with previous transverse surgical scars in the upper abdomen. Often a limited abdominoplasty of the low transverse type with limited undermining only up to the level of the umbilicus is performed in order not to compromise blood supply in the zone between the old transverse and the new transverse scar.

METHOD

We propose a new, modified and safe surgical technique to perform a complete abdominoplasty with wide undermining up to the xiphoid process in patients with preexisting transverse subcostal scars after gastric bypass surgery, by selectively dissecting and preserving one to three periumbilical abdominal wall perforator vessels to secure flap blood supply. Vessel tunnelling through the rectus sheath and muscle and ligation of the cephalad branch of the perforator provide sufficient flap mobility without perforator tension or traction. Flap undermining is performed around these perforator vessels. To match dissected flap perforators with blood-flow, we performed post-operative color-flow duplex scanning.

RESULTS

We treated two patients according to this new technique. In both cases the postoperative course was uneventful and a good aesthetic result was achieved.

CONCLUSION

We conclude from our experience that with this perforator-sparing abdominoplasty technique, safe and complete abdominoplasty can be performed with no additional risk of complications and that a good cosmetic result can be achieved in patients after open gastric bypass surgery.

Obesity Alters Rat Abdominal Flap Survival

Obesity presents a risk factor for flap-related complications in autologous tissue breast reconstruction. In this study, an animal model was developed to examine this phenomenon. Abdominal flaps based on a superficial inferior epigastric pedicle were elevated in an experimental group of obese Zucker (fa/fa) rats (n = 8; mean weight, 413 g) and in their lean littermates (n = 9; mean weight, 276 g). Flap tissue was harvested from a subset of both groups for baseline characterization, including histology, and assays for ATP and oxidative phosphorylation uncoupler, UCP-2. Flaps were then evaluated for survival by planimetry at 4 and 7 days postprocedure. Flap survival 7 days postoperatively was reduced in obese (42.0% ± 8.6%) versus lean (70.3% ± 6.7%) rats ( P < 0.05). At baseline, flap tissue of obese animals had decreased ATP content relative to lean counterparts (0.12 ± 0.12 nM/μg vs 0.36 ± 0.23 nM/μg protein, P < 0.05), whereas UCP2 mRNA was higher in obese flap tissue versus lean. Reduced viability of obese flaps may be attributable to decreased baseline energy stores due to oxidative phosphorylation uncoupling by UCP-2. This study is the first to introduce a promising animal model for examining the effect of obesity on increased flap-related complications in breast reconstruction using autologous tissue.

The Effect of Twisting on Perforator Flap Viability

Perforator flaps increasingly find acceptance and use in the field of reconstructive surgery due to their decreased donor-site morbidity and increased like-tissue coverage. Nevertheless, they are more prone to vascular compromise, especially when the meticulous technique they require is not employed. Pedicle twisting is a condition occasionally encountered in flap procedures, sometimes inadvertently, sometimes inevitably. In this study, circulatory comprise induced by twisting of the pedicle on a true perforator flap in a rat model is investigated.Thirty-eight Wistar-Albino rats were randomized into 4 groups, and cranial epigastric artery true perforator flaps were elevated on a single perforator. The flaps were returned as they were in the control group (n = 9), and with 90 degrees , 180 degrees , and 270 degrees of torsion in groups 2 (n = 9), 3 (n = 10), and 4 (n = 10), respectively. The flaps were evaluated by their flap survival area, weight, and histopathological appearance by the end of the first week. The mean flap survival ratios for groups 1, 2, 3, and 4 were 97.78 +/- 4.41%, 72.22 +/- 44.10%, 73.50 +/- 30.46%, and 30 +/- 30.18% (mean +/- SD), respectively. The degree of degenerative changes in group 4 was found to be statistically significant (P < 0.016).Our histopathological examinations indicate that vascular compromise was moderate in group 3 and severe in group 4. Our findings suggest that under normal conditions, the pedicle of a true perforator flap must not be twisted more than 180 degrees .

Comparison of the effectiveness of gene therapy with transforming growth factor-beta or extracorporal shock wave therapy to reduce ischemic necrosis in an epigastric skin flap model in rats

The induction of neoangiogenesis by exogenous growth factors in failing skin flaps has recently yielded promising results. Gene transfer with virus vectors has been introduced as a highly capable route of administration for growth factors, such as vascular endothelial growth factor or fibroblast growth factor. Extracorporal shock waves (ESW) deliver energy by means of high amplitudes of sound to the target tissue and have been shown to induce angiogenesis. We compared the effectiveness of gene therapy with adenovirus-mediated transforming growth factor-beta (TGF-beta) and ESW therapy to treat ischemically challenged epigastric skin flaps in a rat model. Thirty male Sprague-Dawley rats were divided into three groups of 10 each with an 8 x 8 cm epigastric skin flap. Rats received either subdermal injections of adenovirus (Ad) encoding TGF-beta (10(8) pfu) or ESW treatment with 750 impulses at 0.15 mJ/mm2. The third group received no treatment and served as a control group. Flap viability was evaluated after 7 days and digital images of the epigastric flaps were taken and areas of necrotic zones relative to total flap surface area calculated. Histologic evaluation and increased angiogenesis were confirmed by CD31 immunohistochemistry. Overall, there was a significant increase in mean percent surviving area in the Ad-TGF-beta group and the ESW group compared to the control group (ESW group: 97.7 +/- 1.8% vs. Ad-TGF-beta: 90.3 +/- 4.0% and control group: 82.6 +/- 4.3%; p < 0.05). Furthermore, in the ESW group mean percent surviving areas were significantly larger than in the Ad-TGF-beta group (ESW group: 97.7 +/- 1.8% vs. Ad-TGF-beta: 90.3 +/- 4.0%; p < 0.05). Flap vascularization was increased by Ad-TGF-beta and ESW with numerous vessels, however, there was no significant difference between the two treatment groups. We conclude that treatment with ESW enhances epigastric skin flap survival significantly more than Ad-TGF-beta treatment and thus represents a modality that is feasible, cost-effective, and less invasive compared to gene therapy with growth factors to improve blood supply to ischemic tissue.

Cranial epigastric perforator flap: a rat model of a true perforator flap

The major advantage of a true perforator flap is the ability to capture the skin portion of what previously was a musculocutaneous flap, while totally excluding the muscle for function preservation. To understand better the physiology and dynamics of this flap subtype, a comparable and reliable animal model is essential. This has now been accomplished in the Sprague-Dawley rat using the same abdominal skin territory of the standard rat transverse rectus abdominis musculocutaneous flap, but differing in that all rectus abdominis fascial perforators are isolated via an intramuscular dissection back to the cranial epigastric artery source vessel. Hence, this has appropriately been termed the cranial epigastric perforator flap. From a series of eight rats to date, consistent survival of this flap was as predicted. The dissection itself can be somewhat tedious, but it became easier with experience, making this an excellent training model for learning proper technique in the elevation of any true perforator flap.