This paper describes the steps required to raise a fasciocutaneous epigastric free flap and transfer it to the neck in the rat.
Free tissue transfer has been increasingly used in clinical practice since the 1970s, allowing reconstruction of complex and otherwise untreatable defects resulting from tumor extirpation, trauma, infections, malformations or burns. Free flaps are particularly useful for reconstructing highly complex anatomical regions, like those of the head and neck, the hand, the foot and the perineum. Moreover, basic and translational research in the area of free tissue transfer is of great clinical potential. Notwithstanding, surgical trainees and researchers are frequently deterred from using microsurgical models of tissue transfer, due to lack of information regarding the technical aspects involved in the operative procedures. The aim of this paper is to present the steps required to transfer a fasciocutaneous epigastric free flap to the neck in the rat.
This flap is based on the superficial epigastric artery and vein, which originates from and drain into the femoral artery and vein, respectively. On average the caliber of the superficial epigastric vein is 0.6 to 0.8 mm, contrasting with the 0.3 to 0.5 mm of the superficial epigastric artery. Histologically, the flap is a composite block of tissues, containing skin (epidermis and dermis), a layer of fat tissue (panniculus adiposus), a layer of striated muscle (panniculus carnosus), and a layer of loose areolar tissue.
Succinctly, the epigastric flap is raised on its pedicle vessels that are then anastomosed to the external jugular vein and to the carotid artery on the ventral surface of the rat’s neck. According to our experience, this model guarantees the complete survival of approximately 70 to 80% of epigastric flaps transferred to the neck region. The flap can be evaluated whenever needed by visual inspection. Hence, the authors believe this is a good experimental model for microsurgical research and training.
무료 조직 전송은 점점 1970 1-5 실종 조직을 재구성하기 위해 임상에 사용되고있다. 이는 종양 적출술, 외상, 감염, 기형이나 화상 1-7으로 인한 복잡하고, 그렇지 않으면 치료가 결함의 재건을 허용했다. 이런 종류의 무료 플랩은 머리와 목, 손, 다리들, 그리고 회음부 1,4처럼 매우 복잡한 해부학 적 영역을 재구성 특히 유용하다.
그러나, 오늘은 수술 연수생은 자주 제기 전송 및 미세 수술 기법과 악기 8,9를 사용하여 무료 플랩을 insetting에 관련된 여러 단계의 복잡성에 의해 daunted된다. 또한, 널리 실력 microsurgeon 될 것이 허용되며, 동물 모델에서의 광범위한 실험 방법은 4,8-13 필수적이다.
또한, 기본 및 중개 연구무료 조직 전송 분야에서 큰 임상 전위 8,14-16이다. 그럼에도 불구하고, 연구자들은 자주 인해 수술 절차 4,8-14 관련된 기술적 측면에 관한 정보 부족으로 조직의 미세 수술 전달 모델을 사용 저지된다. 그것은 자주 조작 8,11,13,14,17,18을 유지하기 쉽고, 의무, 상대적으로 저렴 같이 쥐, 미세 수술 연구와 교육을위한 좋은 동물 모델이다.
몇몇 무료 뼈, 근육 및 피부 플랩 래트 18-24에서 설명되었지만, 프리 상복부 fasciocutaneous 플랩 널리 교시 9,12,13,18,25 목적을 위해 사용된다. 이 무료 플랩 어 첫 번째 Strauch 머레이에 의해 1967 년에 기술되었다 인해 여러 가지 요인, 기증자의 영역, 즉 일정한 혈관 해부학, 해부의 상대적 용이성, 상당한 영양 혈관, 피부의 중복에, 그 이후로 인기를 증가 얻고있다무형 문화 유산은 플랩의 고도 4,9-11,13,17,18,25-28에서 발생하는 결함의 기본 폐쇄 할 수 있습니다.
플랩 해부학과 조직학
상복부의 플랩은 표면 상복부 동맥 및 정맥 (그림 1)에 의해 제공됩니다. 이 선박에서 발생한 각각 대퇴 동맥과 정맥에 드레인. 평균적으로 피상적 상복부 혈관의 구경 (그림 2) 17, 18 피상적 인 상복부 동맥의 0.3 ~ 0.5 mm 대조, 0.6 ~ 0.8 mm이다. 측면과 차례로 상복부 지역의 외피의 대부분을 공급하는 모세 혈관 네트워크를 발신, 여러 번 나누어 내측 지점 : 피상적 상복부 동맥 두 가지 주요 지점을 제공합니다. 이러한 모세 혈관은 (그림 2) 13,17,18 동맥 트리 병렬 과정을 피상적 상복부 정맥의 지류로 배출. 그림 3 재에도상복부의 플랩에 동원 할 수있는 피상적 인 상복부의 선박에 의해 공급되는 ventrolateral 복부 벽의 영역을 제공합니다. 이 플랩의 길이는 최대 5cm, 폭 13,17,18에서 3cm 될 수 있습니다.
조직 학적으로, 플랩은 ventrolateral 복벽 근육 (그림 4) 13,17,18를 덮고있는 외피로 구성되어있다. 그것은 진피와 표피에 의해 형성된 피부의 표면 층을 포함하고 있습니다. 피부 아래에 adiposus panniculus라는 지방 조직의 층이있다. 이 층 아래 panniculus의 카르노 서스 18,28,29로 알려진 횡문근의 또 다른 층이있다. panniculus의 카르노 서스 아래 큰 복부 근육을 덮고있는 깊은 근막에 피상적이고 느슨한 유륜 조직이있다. 따라서, 플랩이 깊은 근육 근막을 제외한 모든 층을 포함하는 복합 조직의 블록이다 (도 5) (1)3,17,18,27-31.
The most important aspect to obtain consistent flap survival is paying attention to detail in various steps of the microsurgical technique. For example, to obtain good visualization of the vessels, of the surgical instruments and of the fine suture lines, it is very helpful to place underneath the vessels, a sterilized colored plastic background. As many researchers, we prefer to use sterilized fragments of yellow or green balloons (Figures 7 and 11). This background provides the additional advantage of minimizing adherence of suture lines to the adjacent structures, which sometimes leads to the need of pulling the suture line with too much tension, which may in turn lead to vascular tearing. Finally, the use of a background has the additional advantage of decreasing the probability of inadvertently dragging potential thrombogenic tissue debris to the anastomosis site.
Considering that the flap’s vessels are very fine and fragile, it is important not to pinch the entire width of the vessels, in order to avoid intimal lesion that, in turn, will lead to intravascular thrombosis and flap failure. To prevent inadvertent injury to both the flap’s vessels and to the recipient site’s vessels, it is safer to liberally ligate and divide neighboring tributaries, which will allow an easier manipulation of these vessels.
Before starting the anastomoses, it is vital to place the vessels in their definitive position, striving to prevent vascular kinking or torsion of the flap’s pedicle. Given the small caliber and delicate consistency of the vessels, these are often difficult to exclude unequivocally. One helpful trick is to secure the flap in its final position with 3 stitches placed away from the site of the anastomoses. Next, if in doubt, temporarily open the vascular clamps placed at the flap’s pedicle, and fill the vessels’ lumen with heparinized normal saline in a concentration of 10 IU/mL until they become engorged. This leads vessels to assume the configuration they will present after being perfused by blood, as when the clamps are removed after anastomoses completion.
Moreover, it is of paramount importance to detect any air bubbles, even if small, inside the vessels during the entire procedure and particularly before tying the final stitches. If these bubbles are distant from the vascular section, the vessels can be milked gently with microsurgical forceps. If they are located close to the anastomotic sites, simple irrigation leads the less dense bubbles to be easily expelled from the vascular lumen. Failure to acknowledge the presence of air bubbles can cause irreversible flap ischemia and necrosis, no doubt due to the fine caliber of the flap vessels.
Additionally, it cannot be overemphasized the need for meticulous care while passing and tying the stitches, in order to: include the three layers of the vessels (intima, media and adventitia); obtain good vessel eversion to ensure adequate intimal contact, which is vital to anastomosis sealing and endothelial regrowth; avoid loose vascular contact, which will result in anastomotic incompetence, i.e., bleeding; and avoid grabbing too much vascular tissue, which will lead to anastomosis stenosis and proclivity to thrombosis, which in turn will result in venous congestion or poor flap perfusion, if the vein or artery are involved, respectively.
Finally, it is essential to ensure perfect hemostasis, during the entire procedure, especially when raising the flap in its deep surface. Otherwise hematoma formation and rat death are likely to ensue.
Modifications and troubleshooting of the technique
The authors observed that making a transverse incision in the middle portion of the SCM using an electric cautery, not only allows a better exposure of the carotid artery, but also minimizes the risk of undue tension over the future arterial anastomosis.
Another important technical tip is to start the anastomosis from the vessels’ back wall, in order to minimize the risk of unwillingly catching this wall when placing the stitches in the more easily exposed front wall. If the back wall is sutured to the anterior aspect of the anastomosis, lack of vascular patency will almost invariably result either immediately due to mechanical reasons or after only a few hours as a result of thrombosis8.
If the anastomoses of the epigastric vessels of the rat are considered too technically challenging due to the small caliber of these vessels, the femoral vessels can be ligated distal to the origin of the epigastric vessels and used as the vascular pedicle of the epigastric flap. In this way, larger vessels will be used (the femoral artery has a caliber of 1.0 to 1.2 mm; and the femoral vein has a caliber of 1.2 to 1.5 mm). Moreover, by dissecting and ligating the other tributaries of the femoral vessels, a vascular pedicle length of over 2 cm can be obtained, which will facilitate flap insetting18,34,35.
Reproducibility
Our experience of more than ten years of using this flap for teaching and research purposes strongly suggests that the rat epigastric flap is a reproducible model of free tissue transfer11,13,17,18,26. It can be easily incorporated in microsurgical courses, as it is a good teaching and training model for microsurgery trainees11,13,17,18,26. In our experience, although technically challenging in the beginning for the novice in microsurgery, after some training, the free epigastric flap can be successfully transferred to the neck of the rat with minimal to no subsequent necrosis in 70 to 80% of cases. These results concur with those generally reported in the literature13,18,36.
Significance with respect to existing methods
Numerous free flaps have been described in the rat10,16,18,37-39. The most commonly used for teaching and research purposes have been the transverse rectus abdominis myocutaneous flap, the latissimus dorsi and serratus anterior muscle flaps, the hind limb replantation model, and the epigastric (groin) flap18,35. These flaps have been favored, due to their consistent anatomy and sizeable vascular pedicle. The epigastric flap is arguably the one associated with lesser donor site morbidity, as it dissected above the muscle fascia18. Moreover, the epigastric flap, described in 1967, was the first flap to be described in rats34,35. This occurred only 4 years after the first description of an experimental flap in an animal by Goldwyn. Interestingly, this flap was a groin flap in the dog34.
Limitations of the technique
The two main limitations of this model are the need for microsurgical skills in order to carry out the surgery, and the presence of significant necrosis in 20 to 25% of cases, according to different authors13,18,36. Another potential limitation of the model herein presented is the auto cannibalism of the flap. However, as the authors above, this is an infrequent finding that almost only occurs in cases of total flap necrosis.
Future applications of the technique
The rat epigastric free flap can be used in experimental studies of tissue perfusion, tissue repair and surgical wound infection40,41. Its nutrient vessels are particularly suitable for intravascular injection of solutions containing substances of interest, namely drugs, viral vectors or liposomes, that will mostly produce a local or regional effect30,31. In addition, beneath the flap, pathogens, foreign bodies, radioactive seeds or chemicals can also be placed, mimicking several disease processes and potential treatments30,31.
The authors have nothing to disclose.
저자 (디오 카살) 중 하나는 Fundação Calouste 굴벤 키안, Fundação Champalimaud, Ministério 다 Saúde 전자 Fundação 파라 Ciência 전자 TECNOLOGIA, 포르투갈 후원 고급 의료 교육을위한 프로그램에서 보조금을 받았다.
저자는 촬영과 비디오를 편집 씨 알베르토 세 베리의 기술적 도움을 감사의 말씀을 전합니다. 저자는이 논문에서 제시 한 동물 표본을 준비하는 그들의 도움 씨 옥타비오 Chaveiro 씨 마르코 코스타 씨 카를로스 로페스에 감사하고 있습니다.
마지막으로, 저자는 동물의 획득 및 유지 보수에 관한 모든 물류 측면에서 그녀의 도움을 양 Gracinda 메네 제스에게 감사의 말씀을 전합니다.
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Micro retractor | Fine Science Tools | RS-6540 | http://www.finescience.de |
Graeffe forceps 0.8 mm tips curved | Fine Science Tools | 11052-10 | http://www.finescience.de |
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Clamp applicator | Fine Science Tools | CAF-4 | http://www.merciansurgical.com/acland-clamps.pdf |
High-Temperature Cautery | Fine Science Tools | AA03 | http://www.boviemedical.com/products_aaroncauteries_high.asp |
Micro-vessel dilators 11 cm 0.3 mm tips 00124 | Fine Science Tools | D-5a.2 | http://www.merciansurgical.com |
Micro Jewellers Forceps 11cm angulated 00109 | Fine Science Tools | JFA-5b | http://www.merciansurgical.com |
Micro Jewellers Forceps 11 cm straight 00108 | Fine Science Tools | JF-5 | http://www.merciansurgical.com |
Acland Single Clamps B-1V (Pair) | Fine Science Tools | 396 | http://www.merciansurgical.com |
Micro Scissors Round Handles 15 cm Straight | Fine Science Tools | 67 | http://www.merciansurgical.com |
Iris Scissors 11.5 cm Curves EASY-CUT | Fine Science Tools | EA7613-11 | http://www.merciansurgical.com |
Mayo Scissors 14 cm Straight Chamfered Blades EASY-CUT | Fine Science Tools | EA7652-14 | http://www.merciansurgical.com |
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Monosyn 5-0 | B.Braun | 15423BR | http://www.mcfarlanemedical.com.au/ 15423BR/ SUTURE-MONOSYN-5_or_0-16MM-70CM-(C0023423)-BOX_or_36/pd.php |
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Veet Sensitive Skin Hair Removal Cream Aloe Vera and Vitamin E 100 ml | Veet | http://www.veet.co.uk/products/creams/creams/veet-hair-removal-cream-sensitive-skin/ | |
Instrapac – Adson Toothed Forceps (Extra Fine) | Fine Science Tools | 7973 | http://www.millermedicalsupplies.com |
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Straight mosquito forcep | Fine Science Tools | 91308-12 | http://www.finescience.de |
Cutasept F skin disinfectant | Bode Chemie | http://www.productcatalogue.bode-chemie.com/products/skin/cutasept_f.php | |
Lacri-lube Eye Ointment 5g | Express Chemist | LAC101F | http://www.expresschemist.co.uk/lacri-lube-eye-ointment-5g.html |
Normal saline for irrigation | Hospira, Inc. | 0409-6138-22 | http://www.hospira.com/en/search?q=sodium+chloride+irrigation%2C+usp&fq=contentType%3AProducts |
Heparin Sodium Solution (5000IU/ml) | B.Braun | http://www.bbraunusa.com/products.html?prid=PRID00006982 | |
Meloxicam Metacam | Boehringer Ingelheim | http://www.bi-vetmedica.com/species/pet/products.html | |
Heat Lamp HL-1 | Harvard Apparatus | 727562 | https://www.harvardapparatus.com/webapp/wcs/stores/servlet/ haisku3_10001_11051_39108_-1_ HAI_ProductDetail_N_ 37610_37611_37613 |
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Dry heat sterilizer | Quirumed | 2432 | http://www.quirumed.com/pt/material-de-esterilizac-o/esterilizadores |
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Operating microscope | Leica Surgical Microsystems | 10445319 | http://www.leica-microsystems.com/products/surgical-microscopes/ |