WHAT IS AN SIEA PERFORATOR (SIEP) FLAP?
The SIEA Perforator (SIEP) Flap uses the same tissue but is based on the Superficial Inferior Epigastric Artery (perforator) of the groin and includes the skin and subcutaneous tissues of the lower abdomen.
This flap consists of the same abdominal skin and fatty tissues as the DIEP flap, but has a different vascular pedicle called the superficial inferior epigastric artery. This flap may be used in women where these superficial vessels are the principal blood supply to the lower abdomen.
This flap can be used for either immediate or delayed reconstruction of the breast. The skin and subcutaneous (fat) tissues of this flap are from the lower abdomen and the same as those of the DIEP flap, but have a different vascular pedicle have the blood supply.
The SIEA perforator flaps vascular supply is the superficial Inferior epigastric artery and vein. These vessels lie above the fascia of the rectus abdominis muscle, and therefore unlike the DIEP flap, the SIEA perforator flap can be harvested without the having to cut the rectus sheath or dissect through the rectus muscle.
When this vascular pattern is available, the SIEA flap may be chosen over a DIEP flap due the advantages or not violating the rectus muscle or fascia and a shorter operating time. However, even if preoperative evaluation find the SIEA flap is possible, a final decision will be made intra-operatively, at the time of surgery. This is because the superficial epigastric vessels may not be adequate in size, then a DIEP flap will usually then be performed.
The lower abdominal elliptical design of the SIEA perforator flap is the same as for the DIEP perforator flap. Intra-operative evaluation will determine whether the vascular pattern will support a flap that crosses the midline. Tailoring of the excess tissues to shape the breast mound is the same for a DIEP flap as well. Importantly, the SIEA perforator flap includes no muscle or rectus sheath, and consists of its vascular pedicle, and the skin and subcutaneous (fat) that it supplies.
The SIEA perforator flap can be harvested as a single flap or as a two flaps for bilateral breast reconstruction. Once the flap is dissected so that it is attached only by its vascular pedicle the edges are assessed for bleeding to determine if some areas that lack sufficient blood supply and need to be trimmed.
The chest wall dissection of the internal mammary vessels is performed through the mastectomy incision, which may be lengthened for better exposure. These vessels are then prepared for microvascular anastamosis.
Once the internal mammary vessels are ready the pedicle of the SIEA perforator flap is tied off at its base and divided. The flap is then brought to the mastectomy site where the pedicle vein and artery are repaired to the internal mammary vessels. Once these vascular repairs are accomplished, the circulation of the SIEA perforator flap is immediately re-established. The abdominal was is intact as no surgery in the rectus sheath or rectus abdominis muscle was involved. The abdominal wound is then closed as an abdominoplasty.
The flap is then further shaped, trimmed and inset to create a symmetrical breast mound as possible.
Sometimes, reduction of the opposite breast is necessary to improve symmetry. This is done at a later procedure. Also later after adequate healing has occurred and breast symmetry has been achieved nipple areola reconstruction can be performed.
Since the SIEA Perforator Flap utilizes the vessels above the muscle and fascia, it therefore, leaves them undisturbed. Because of this there is less post operative pain and no risk of hernia. However, this vascular pattern often may not be present, and therefore a DIEP Flap is used. Although the vascularity is evaluated before the operation, a final decision on which flap to do is not made until examination of the vascularity in the operating room.