An economical axial-pattern flap necrosis model

A new lateral thoracic artery perforator flap design with multiple vascular territories in rats

BACKGROUND

To describe a new design for an extended lateral thoracic artery (LTA) perforator flap and investigate its anatomical, dynamic, and potential territories.

MATERIALS AND METHODS

To assess vascular territories, rats were randomized according to LTA perforator flap type into the surgical groups A, hemidorsal island flap; B, entire dorsal island flap; and C, reduced-size dorsal island flap.

RESULTS

On postsurgical day 7, the surviving flap areas were 95%, 92%, and 89% in groups A, B, and C, respectively. Necrosis most commonly occurred in the contralateral LTA territories in groups B and C. The immunoreactivities of intercellular adhesion molecule 1 and vascular endothelial growth factor receptor 2 in dynamic territories, as choke vessel markers, were increased.

CONCLUSIONS

We clarified the LTA perforator flap nomenclature and defined its pedicle course and anastomosing patterns; furthermore, we demonstrated that the LTA perforator did not anastomose with its counterpart because of its unidirectional, oblique, and craniocaudal course. The LTA perforator flap was found to be a good model comprising multiple vascular territories and exhibiting continuous necrosis.

Enhanced random skin flap survival by sustained delivery of fibroblast growth factor 2 in rats

BACKGROUND

Skin flap survival is a major challenge in reconstructive plastic surgery. Here, we examined the effect of sustained delivery of fibroblast growth factor 2 (FGF2) using heparin-conjugated fibrin (HCF) on skin flap survival in rats.

METHODS

Rats with a skin flap received either phosphate-buffered saline/FGF2 or HCF/FGF2 in the recipient bed. For the no-treatment group, a random skin flap was sutured on the back without any treatment. Seven days after surgery, angiogenesis in the skin flap was evaluated by using Visitrak system and conventional healing quality scoring method. The efficacy of HCF/FGF2 in skin flap survival was evaluated by comparing the results from different groups.

RESULTS

The necrotic area of the skin flap significantly decreased in the HCF/FGF2 group as compared with the other groups.

CONCLUSION

The sustained delivery of FGF2 using HCF has a therapeutic potential to improve skin flap survival.

Rat dorsal paired island skin flaps: a precise model for flap survival evaluation

Rectangular flaps on the rat or mouse dorsum are frequently used for flap survival elongation research. However, since rectangular flaps are purely random, the survival rate varies among individuals. A reliable animal flap model with low individual variation is desirable for flap survival research, especially in the angiogenic field. We investigated the survival rate of paired flaps in the rat dorsum containing 3 vascular territories in each flap, and determined their usefulness for flap elongation research. Two symmetrical adjoining rectangular flaps (11 x 3 cm each) were drawn on the rat dorsum. Two days after material injection, flaps were elevated with only the deep circumflex iliac vessels as the vascular pedicle. Flaps were immediately sutured back and the flap survival area was measured 7 days after the operation. The control group (n = 9) had saline solution injected in both flaps. The bone marrow group (n = 8) had bone marrow injected in the right flap, and saline solution injected in the left flap. In the control group, the survival rate of the paired flaps was not statistically different (right flap, 89.0+/-5.6%; left flap, 89.3+/-4.5%). In the bone marrow group, the survival rate between the bone marrow injected flap (89.9+/-3.7%), and the saline flap (84.8+/-4.3%) was statistically different. The rat dorsal paired island skin flap model shows low difference in flap survival rate and uses an internal control. This is a suitable model for flap survival elongation research.

Selective Percutaneous Desiccation of the Perforators with Radiofrequency for Strategic Transfer of Angiosomes in a Sequential Four-Territory Cutaneous Island Flap Model

BACKGROUND

Research in prevention of partial flap necrosis has recently concentrated on extending the safe length of a flap by ligating vessels of known territories. To advance this approach one step further, the authors decided to reveal the least invasive surgical strategy for transfer of angiosomes.

METHODS

The study was arranged into three experiments. In the first experiment (n = 17 rabbits), a cutaneous island flap model spanning four adjacent vascular territories was developed. In the second experiment (n = 15 rabbits), the flap model was used to test the possibility of desiccating those vessels supplying the angiosomes to be captured percutaneously with radiofrequency. The delay procedures were performed by means of minimal skin incisions, and the flaps were elevated after a 2-week delay period. In the third experiment, the effectiveness of selective interference of these pedicles was compared to minimize the number of target vessels for successful transfer of angiosomes.

RESULTS

The mean surviving area of the new flap model was 63 +/- 2 percent. The mean surviving flap area was 97 +/- 3 percent for the endoscopy equivalent technique and 94 +/- 4 percent for radiofrequency delay. The results were statistically insignificant between these two groups. In experiment 3, comparison of the results yielded a statistically insignificant difference for flap survival area among all four of the groups.

CONCLUSIONS

An alternative flap model is introduced for future investigation of the vascular delay process. Percutaneous desiccation of the perforators with radiofrequency was found to be a reliable method, and selective desiccation of the perforator(s) was as efficient as destruction of all vascular sources other than the pedicle.

An ameliorated skin flap model in rats for experimental research

There is a disagreement in the experimental design of random skin flaps owing to their vascular inconsistency. The definition of a reliable axial-pattern skin flap model is needed. The purpose of this study was to describe a new skin flap model to deal with entire drawbacks of existing random and axial pattern skin flap designs. This was accomplished by creating paired skin flaps including both skin and vascular pedicle on the dorsum of the same rat. This design was suitably termed as rando-axial flap. The present study offers a simple and reliable skin flap model with following advantages: (1) it has a predictable necrosis area, (2) it reveals a larger survival area (75 +/- 5%) when compared to other flaps in this study (Mann-Whitney U-test, p<0.001), (3) the vascular pedicle is consistent, (4) control and study flaps are placed on the same animal (5) it can be converted to a random, an axial or a free flap.

Gene transfer of bFGF to recipient bed improves survival of ischemic skin flap

BACKGROUND

The recipient bed is a promising target of angiogenic therapy to treat ischemic skin flaps. We delivered basic fibroblast growth factor (bFGF) gene to the recipient bed by a plasmid-based method with electroporation, and assessed the effects on flap viability in a rat dorsal skin flap model.

METHODS

A 25 x 90 mm(2) axial skin flap was elevated on the back of male Sprague-Dawley rats. Two days before flap elevation, an expression plasmid vector containing the bFGF gene with the signal sequence was injected into the dorsal muscles beneath the skin flap, and then electroporation was delivered (FGF-E(+) group). As control, rats were injected with a plasmid vector containing LacZ gene (LacZ-E(+) group), instead of bFGF gene. Other groups of animals received plasmid vector containing bFGF (FGF-E(-) group) or LacZ (LacZ-E(-) group) gene without electroporation. Seven days later, the area of necrosis and neovascularisation of the skin flap were evaluated.

RESULTS

The bFGF gene was successfully transferred to the dorsal muscles, and bFGF was expressed in muscle tissue. The area of flap necrosis (%) in the FGF-E(+) group (21.7+/-5.3%) was significantly smaller than that in the LacZ-E(+) (28.3+/-4.1%), FGF-E(-) (29.7+/-3.3%), and LacZ-E(-) (28.1+/-2.5%) groups. Postmortem angiograms and histological analyses showed that vascularisation in the distal part of the skin flap was significantly increased in the FGF-E(+) group compared with the other groups.

CONCLUSION

These findings suggested that gene delivery of bFGF to the recipient bed muscles enhanced vascularity and viability of an ischemic skin flap, and that plasmid-based gene delivery with electroporation was a suitable delivery method.

An extended dorsal island skin flap with multiple vascular territories in the rat: A new skin flap model

BACKGROUND

The use of various animal skin flap models can lead to difficulty in the interpretation of experimental findings. Establishment of an axial-pattern flap model with predictable necrosis is desirable for the study of the flap pathophysiology.

MATERIALS AND METHODS

Twenty rats were injected with a lead oxide, gelatin, and water mixture through the carotid artery to investigate the cutaneous vascular anatomy. Each cutaneous perforator on the rat dorsum was dissected to its source artery. The skin was removed and radiographed to define its vascular architecture. On the basis of the initial angiographic data, an extended dorsal island skin flap (based on the unilateral deep circumflex iliac artery) measuring up to 8 x 9 cm was designed in 10 rats to assess the viability of the flap. The boundaries of the flap are defined by anatomical landmarks to standardize the flap for rats of different sizes. The upper margin was located at the level of the tip of the scapula and the lower margin at a level 2 cm below the iliac crest. All flaps were observed for 7 days postoperatively and the surviving flap area was calculated as a percentage of total flap dimensions using the paper template technique.

RESULTS

Most of the skin of the rat dorsum is supplied by three arteries: the deep circumflex iliac artery (DCIA), the posterior intercostal arteries (PIA), and the lateral thoracic artery (LTA). The DCIA anastomoses with the ipsilateral PIA and the contralateral PIA and DCIA. The average percentage survival of the skin flap is 70.5 +/- 4.8% (mean +/- SD).

CONCLUSIONS

The extended dorsal island skin flap has a consistent vasculature and has a predictable distal necrosis area. This new model is felt to be appropriate for skin flap physiological studies.