Porcine model for deep superior epigastric artery perforator flap harvesting: Anatomy and technique

BACKGROUND Microsurgical training on rats before starting with clinical practice is a well-established routine. Animal model training is less widespread for perforator flaps, although these flaps represent a technical challenge. Unlike other flaps, they require specific technical skills that need to be adequately trained on a living model 1 : a cadaver is not enough because no bleeding, vessel damage, or vasospasm can be simulated. 2 The purpose of this study was to assess the suitability of the porcine abdomen as a training model for the deep inferior epigastric artery perforator (DIEAP) flap, commonly used in human breast reconstruction. METHODS A female swine (Sus scrofa domesticus, ssp; weight 25kg) was used. The procedure was performed with the pig under general anesthesia and in the supine position. A deep superior epigastric artery perforator (DSEAP) flap was harvested on the left side of the abdomen, including the 3 cranial nipples and stopping in the midline to spare the contralateral flap for another dissection (as in bilateral breast reconstructions in humans; Fig. 1). All steps of a DIEAP harvest were simulated: superficial vein harvest, suprafascial perforator dissection, intramuscular perforator harvest with preservation of the nerves, and flap isolation. Observation of capillary refill was used to confirm flap viability at the end of the dissection. The procedure was recorded by means of a GoPro camera and simultaneously with a head mounted (4× magnification) Loupecam system. Photographs were taken using 2 cameras during surgery at relevant time points. RESULTS At the end of the dissection, the flap was viable. The subcutaneous adipose tissue of the pig is less represented than in human and pigs have an additional muscular layer, the panniculus carnosus, which is the analogue of the human Scarpa's fascia. The rectus fascia is thinner. The perforators are lined in 2 rows: 1 lateral and 1 medial, as in the DIEAP, and the intercostal nerves cross the vessels, as happens in humans. The porcine rectus abdominis muscle is thinner than the human one, but vessels' branching faithfully reproduces the human model. 1 We identified 5 perforating vessels of more than 1mm in diameter (2 lateral and 3 medial). We isolated a lateral perforator first and a medial one last: the latter was eventually used to nourish the flap (Fig. 2). CONCLUSIONS The DSEAP flap allows one to closely reproduce all the steps of DIEAP flap harvesting and also to carry out the intramuscular dissection of 2 perforators for each side (up to 4 for each animal), confirming the adequacy of this pig model for microsurgical training. The deep superior epigastric artery is dominant in pigs. 3 Despite this anatomical difference, the DSEAP allows one to reproduce the main steps of DIEAP flap harvesting, providing an excellent training model. Moreover, the presence of double perforating rows allows simulating the dissection twice on each side.