Abdominal Breast Reconstruction Using a SIEA Flap Approach



Abdominal Breast Reconstruction Using a SIEA Flap Approach


Adrian S. H. Ooi

Deana Shenaq

Julie E. Park

David H. Song





DEFINITION



  • Abdominal-based flaps for breast reconstruction can be divided into pedicled and free flaps based on their arterial supply.



    • Pedicled



      • Transverse rectus abdominis myocutaneous (TRAM) flap


    • Free



      • TRAM flap


      • Muscle-sparing TRAM (MS-TRAM) flap


      • Deep inferior epigastric perforator (DIEP) flap


      • Superficial inferior epigastric artery (SIEA) flap


  • The free TRAM, MS-TRAM, and the DIEP flaps are based on a deep inferior epigastric vascular pedicle arising directly from the external iliac vessels.



    • In the free TRAM flap, the entire width of rectus muscle is taken to capture all the perforators within that segment.


    • In the MS-TRAM flap, a cuff of rectus muscle is harvested to capture multiple perforators from the deep inferior epigastric pedicle.


    • In the DIEP flap, only the perforating vessels to the subcutaneous fat and skin are harvested and the rectus muscle is not sacrificed.






    FIG 1 • Vascular anatomy of the superficial inferior epigastric system.


  • The SIEA flap is based on the subcutaneous superficial inferior epigastric vascular pedicle arising from the femoral vessels in the femoral triangle. Harvest of the flap does not involve any rectus muscle or fascia.


ANATOMY



  • The SIEA flap is a Mathes and Nahai fasciocutaneous type A flap, harvested from the lower abdomen.



    • The skin island for the SIEA flap extends laterally to the anterior superior iliac spine (ASIS), medially to the midline or just past it, and from the level of the umbilicus superiorly to the pubic tubercle inferiorly.


  • Vascular anatomy



    • Arterial



      • The SIEA is a branch of the femoral artery and arises from the femoral artery 2 to 3 cm below the inguinal ligament (FIG 1).


      • It is present in 49% to 91% of patients.1,2


      • The average size of the SIEA is 1.2 to 1.6 mm and average length 4 to 6 cm.3


      • It is present in both groins in 58% of patients.4



      • In about 75% of cases, it arises from a common origin with the superior circumflex iliac artery (SCIA).5


      • The course of the artery is variable in relation to the superficial inferior epigastric vein (SIEV), usually arising up to 3 cm lateral to the SIEV and deep to the Scarpa fascia.


      • After piercing the cribriform fascia, the SIEA courses inferolaterally for a short distance immediately above the deep fascia.


      • It runs in a superolateral direction before crossing the inguinal ligament at roughly the midpoint between the pubic tubercle and the ASIS.


      • The SIEA then pierces the Scarpa fascia to run in the superficial fatty later of the abdomen before arborizing with the periumbilical perforators of the deep inferior epigastric artery.


    • Venous drainage



      • The venous drainage of the flap is through up to two venae comitantes of the epigastric artery and/or the SIEV (see FIG 1).


      • Diameter: 1.3 to 4 mm1


      • The surface marking of the SIEV is one-third of the way between the pubic symphysis and the ASIS.


      • The SIEV directly drains the subcutaneous plexus and is usually located superficial and medial to the SIEA in the superficial fatty layer of the abdomen.


      • The venae comitantes of the SIEA typically drain into SIEV.6


      • Occasionally, the superficial circumflex iliac vein (SCIV) and SIEV join into a common branch before draining into the femoral vein and if taken together can be used to enhance venous drainage of the flap (FIG 2).


    • Flap vascular territory



      • The literature consists of varying reports using different measurement parameters stating flap perfusion can range from the hemiabdomen to 100% of the entire abdominal flap.1,2,6


      • We have found harvesting of the tissue across the midline to be unreliable, and would not advocate going past the hemiabdomen without testing perfusion either clinically with clamping off all other vascular input on the contralateral side or utilizing intraoperative fluorescence imaging.


  • The flap receives sensory innervation via the segmental intercostal nerves T10-T12.


PATHOGENESIS



  • Breast defects requiring SIEA flap reconstruction can be partial or total mastectomy defects and can arise from a variety of pathologies including:



    • Postcancer resection






      FIG 2 • The left superficial inferior epigastric (SIEV) and superficial circumflex iliac veins (SCIV) draining into a common branch.


    • Prophylactic resection


    • Failed implants


  • A single large mastectomy defect may require a complete abdominal flap for coverage. An SIEA flap can be used together with the contralateral SIEA, DIEP, or MS-TRAM flap.


  • The SIEA flap has been used for coverage of other defects including:



    • Head and neck


    • Upper extremity and hand


    • Lower extremity


NATURAL HISTORY



  • Holmström reported the first use of a free abdominoplasty flap based on the deep inferior epigastric vessels in 1979.7


  • Hartrampf pioneered the use of the pedicled TRAM flap for breast reconstruction in 1982.8


  • While sacrificing rectus muscle, the free TRAM gained increasing popularity for breast reconstruction due to the use of the dominant blood supply to the rectus muscle, the deep inferior epigastric pedicle, to perfuse the abdominal tissue. It also allowed for more freedom in insetting and shaping the breast.9


  • To minimize donor-site morbidity from harvest of the rectus muscle, the free MS-TRAM and DIEP flaps were developed following improvements in microsurgical knowledge and technique. Varying amounts of rectus muscle are left behind after harvest to maintain abdominal wall integrity and strength.


  • Further evolution of the abdominal tissue flaps led to the development of the SIEA flap. The flap, first used by Antia and Buch for facial reconstruction in 1971 and further elucidated by Taylor and Daniel in their cadaveric studies of 1975, is based on a subcutaneous pedicle and completely spares the rectus fascia and muscle. Grotting first reported on its use in breast reconstruction in 1991, and owing to its obvious donor-site benefits has rapidly gained popularity ever since.10,11,12


PATIENT HISTORY AND PHYSICAL FINDINGS



  • A focused history and examination relevant to any form of free flap reconstruction should be performed. In particular, the following should be elucidated and corrected if possible:



    • History of tobacco use


    • Obesity


    • Previous irradiation


    • Prothrombotic conditions


    • Anticoagulant use


  • Similar criteria are applied to the SIEA flap as when determining the suitability of a patient for a free DIEP, MS-TRAM, or TRAM.



    • Sufficient redundant lower abdominal skin and fat



      • Approximates final desired breast volume


      • Allows for primary donor-site closure analogous to an abdominoplasty


    • Abdominal scars



      • Transverse lower abdominal scars such as in a Pfannenstiel incision may preclude the use of the SIEA or even deep inferior epigastric pedicles.


      • Midline laparotomy scars limit the abdominal tissue use to a single hemiabdomen as the perfusion across the midline is no longer reliable.



IMAGING



  • Though not essential, several preoperative investigative techniques can be used to elucidate the vascular anatomy of the abdominal flap.



    • Doppler ultrasound



      • Can be used pre- and intraoperatively to locate perforators and pedicle position.


      • Used postoperatively for flap monitoring


    • CT-angiogram and MR-angiogram



      • Used preoperatively to elucidate location of abdominal perforators and the route of the source vessels


      • Can be used to select cases where the SIEA is suitable for use


    • Fluorescence imaging



      • Intraoperative administration of ICG via a peripheral vein after the hemiabdominal flap has been isolated on its pedicle and imaging with an infrared camera can help to assess the flap vascular territory.




DIFFERENTIAL DIAGNOSIS



  • Reconstructive options for breast defects include but are not limited to:



    • Implant-based reconstruction +/− acellular dermal matrix



      • Immediate implant


      • Primary expander with implant exchange


      • Expander-implant


    • Pedicled flaps



      • Latissimus dorsi (LD)


      • TRAM


    • Free flaps



      • LD


      • TRAM


      • MS-TRAM


      • DIEP


      • SIEA


      • Superior gluteal artery perforator (SGAP) flap


      • Inferior gluteal artery perforator (IGAP) flap


      • Gracilis muscle-based flaps


      • Anterolateral thigh


      • Pudendal artery perforator (PAP) flap


      • Lateral thigh perforator (LTP) flap






FIG 3 • A. If anastomosis to the internal mammary vessels is planned, a contralateral SIEA flap is used. B. If anastomosis to the thoracodorsal system is planned, an ipsilateral SIEA flap is used.


SURGICAL MANAGEMENT

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Dec 6, 2019 | Posted by in Reconstructive microsurgery | Comments Off on Abdominal Breast Reconstruction Using a SIEA Flap Approach

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