Breast reconstruction is commonly accomplished with autologous tissue flaps from the lower abdomen and back, prosthetic breast implants, or a combination of both flaps and implants (1). It is generally held that autologous tissue flaps from the lower abdomen are capable of reconstructing a breast with the shape, softness, mobility, and warmth of a natural breast that is not possible when using prosthetic breast implants. However, lower abdominal flap methods involve longer surgical times, longer inpatient hospital stays, longer recovery periods, and some extent of donor-site morbidity that is not associated with methods using breast implants alone.

The last two decades have seen an evolution of techniques for harvesting the lower abdominal flap of skin and subcutaneous tissue for breast reconstruction. The goal has been to minimize the amount of rectus abdominis muscle and anterior rectus fascia that is harvested with the flap in order to decrease donor-site weakness and morbidity. Techniques range from removal and defunctionalization of the entire rectus abdominis muscle in pedicled transverse rectus abdominis myocutaneous (TRAM) flaps, to excision of a segment of muscle and fascia in free TRAM flaps, to removal of a plug of muscle and fascia in muscle-sparing free TRAM flaps, to only incision into the muscle and fascia for deep inferior epigastric artery perforator (DIEP) flaps. Nevertheless, all of the free flap methods involve removal of the deep inferior epigastric artery, which provides the dominant blood supply to the rectus abdominis muscle. Therefore abdominal donor-site morbidity, which can include abdominal motor weakness, pain, and the risk for lower abdominal bulge or hernia formation, cannot be completely prevented with these methods.

The relative donor-site morbidity of free TRAM flaps, muscle-sparing free TRAM flaps, and DIEP flaps has been extensively debated in the literature (2,3,4,5,6,7,8,9,10). It seems that patients who have had DIEP flaps retain more abdominal motor strength postoperatively than patients who have had free TRAM flaps (2,3). However, this difference in strength, as measured by dynamometry, is probably not clinically significant, given that patients do not differ in their ability to perform sit-ups postoperatively (7) and do not differ when questioned about abdominal donor-site morbidity (2,3,4,8).

The superficial inferior epigastric artery (SIEA) flap includes the same paddle of lower abdominal skin and subcutaneous tissue as TRAM and DIEP flaps that works so well for breast reconstruction, but it involves neither incision nor excision of rectus abdominis muscle, anterior rectus fascia, nor the deep inferior epigastric artery. This is because the SIEA flap is a fasciocutaneous flap whose pedicle is the superficial inferior epigastric artery, which has a subcutaneous course from its origin from the femoral artery (11). Therefore use of the SIEA flap can virtually eliminate abdominal donor-site motor weakness and the risk of abdominal bulging or hernia formation.

The SIEA flap for breast reconstruction was first described in 1991 as a “free abdominoplasty flap” in a case report by Grotting (12). Over the next 13 years additional reports of the use of the SIEA flap for breast reconstruction appeared by Volpe et al. (13), Arnez et al. (14), and Chevray (15). This was during a time when free TRAM and DIEP flaps had become popular and were being performed with increasing frequency in many academic medical centers.

The SIEA flap for breast reconstruction has been studied further in the last 5 years. I and others have found that abdominal donor-site morbidity can be virtually eliminated by using the SIEA flap. Postoperative recovery and length of hospital stay are largely determined by healing at the abdominal donor site when using lower abdominal flaps for breast reconstruction. I have shown that patients having unilateral breast reconstruction with SIEA flaps have a significantly shorter inpatient hospital stay than patients who have breast reconstruction with muscle-sparing free TRAM or DIEP flaps (15). In addition, patients who had bilateral breast reconstruction in which at least one of the two lower abdominal flaps was an SIEA flap reported significantly less abdominal donor-site morbidity than patients who had any combination of muscle-sparing free TRAM or DIEP flaps for bilateral breast reconstruction (8).

Despite the definite advantages of decreased abdominal donor-site morbidity, there are two reasons that the SIEA flap cannot be used for every patient and has not become routine. First, in the majority of patients the SIEA is not present or is not large enough to perfuse the entire flap required for breast reconstruction. Second, the SIEA flap has been found to be less reliable, with a significantly higher rate of vessel thrombosis and total flap loss than free TRAM and DIEP flaps (15,16,17).

It is not clear why the SIEA flap has a higher rate of microvascular thrombotic complications. One reason is probably the smaller caliber of the SIEA compared to the DIEA, which makes microvascular arterial anastomosis technically more demanding and therefore less reliable. However, this is probably not the only reason. The smaller diameter of the SIEA also leads to a size mismatch with the recipient internal mammary artery (IMA). This size mismatch is in the unfavorable direction of blood flow from the larger IMA into the smaller SIEA, which in theory has a higher risk of causing an intimal flap or intimal dissection of the SIEA. Moreover, in my experience the SIEA has more fragile intima than the DIEA and tends to suffer intimal tears at branch points during vessel dissection and from mechanical dilation with instruments more easily than the
DIEA. The reasons remain to be proven, but in the hands of experienced microsurgeons, even when using minimum SIEA diameters of 1.5 mm, the SIEA flap remains less reliable than free TRAM and DIEP flaps (15,16,17).

Any patient who is a candidate for breast reconstruction using TRAM or DIEP flaps can be considered for breast reconstruction using an SIEA flap. However, the variable vascular anatomy of the SIEA allows the procedure to be used successfully in only a minority of patients. Thus, patients cannot be guaranteed breast reconstruction with an SIEA flap. In my practice approximately 20% of patients having free flap breast reconstruction from the lower abdomen have an SIEA flap used.

The external diameter of the SIEA often does not increase substantially as the vessel is dissected toward its origin from the femoral artery. Therefore, the external diameter of the SIEA encountered in the vicinity of the lower abdominal flap incision is often a good indication of its diameter at its origin. This is unlike the deep inferior epigastric artery of free TRAM and DIEP flaps, which gradually increases in diameter more proximally toward its origin from the external iliac artery and is often in the range of 2.5 to 3.0 mm in external diameter near its origin.

Patients in whom greater than one half of the available lower abdominal donor tissue is necessary to reconstruct a large enough breast are usually not candidates for breast reconstruction with an SIEA flap. This is because a unilateral SIEA pedicle typically cannot perfuse and drain zone 4 or all of zone 3 across the vertical midline of the lower abdominal flap (18). However, there are rare cases where the territory perfused by the SIEA and drained by the superficial inferior epigastric vein (SIEV), that is its angiosome, is large enough and extends across the midline to support nearly an entire lower abdominal flap (Fig. 68.1).

Patients having bilateral breast reconstruction are ideal candidates for use of an SIEA flap. Since 2 hemi lower abdominal flaps will be used, neither flap will cross the midline to include zone III or IV. If an SIEA flap can be used for at least one of the two hemi lower abdominal flaps, then the abdominal donor site becomes functionally the same as a unilateral donor site. This is because the SIEA flap harvest from one side of the bilateral abdominal donor site involves neither incision nor excision of any rectus abdominis muscle or fascia. This is significant because bilateral free TRAM and DIEP flap patients have significantly greater abdominal donor-site morbidity than patients having unilateral free TRAM and DIEP flap procedures (6). Therefore, patients having bilateral breast reconstruction in which at least one of the two flaps is an SIEA flap have significantly less abdominal donor-site morbidity than patients who have bilateral reconstruction with TRAM or DIEP flaps (8).

Prior chemotherapy or chest wall radiation are not contraindications for breast reconstruction using an SIEA flap. I like to wait at least 1 month after the completion of cytotoxic chemotherapy to allow the patient’s white blood cell count and immune system to recover. I explain to patients that the average cosmetic result of breast reconstruction in a radiated field is inferior to results obtained in a field that has not been treated with radiation. Plastic surgeons in general like to wait 6 to 18 months after radiation before embarking on breast reconstruction. I tell patients that we can proceed 6 months following completion of radiation treatments.

Many surgeons who perform microsurgical free flap breast reconstruction consider a body mass index (BMI) of greater than 35 kg/m² to be a contraindication for free TRAM, DIEP, or SIEA flap surgery. I have found that obesity does not increase the risk for free flap loss but does increase the risk of wound-healing complications and increase surgical time. Many obese patients have excellent aesthetic results because there is ample donor tissue volume to reconstruct even very large breasts and ample flap skin surface area to recreate a ptotic breast, even in delayed reconstruction (Fig. 68.2) in a radiated field, when the skin surface area requirements for breast reconstruction are greater than for immediate breast reconstruction. The results of autologous tissue breast reconstruction in obese patients are on average superior to those for tissue expander and implant reconstruction. This is because one typically needs 500 to 600 cc of tissue expander volume simply to fill the concave chest wall soft tissue defect just to get back to a flat chest following mastectomy in an obese patient. Tissue expanders and implants that are large enough to adequately reconstruct the breasts of patients having a BMI of 35 kg/m² or greater, that is 1,000 cc or more, are not available from the major breast implant manufacturers in the United States.

I feel comfortable performing SIEA flap breast reconstruction on patients with a BMI up to 40 kg/m² and even slightly greater (Fig. 68.3). One of the advantages of SIEA flaps on obese patients is that the SIEA can be 2 mm or larger in external diameter, making for a better size match with the recipient internal mammary artery and making the microsurgery technically easier and more reliable. The disadvantage of operating on obese patients is that operative times are increased in proportion to the BMI and there is a higher rate of wound-healing complications.

Smoking is a relative contraindication to breast reconstruction with an SIEA flap, as it is with any lower abdominal flap. Active smokers are counseled to stop, or at least to abstain for 2 weeks before and after the free flap surgery. Some surgeons will not perform lower abdominal free flap breast reconstruction surgery on patients who are actively smoking and may test urine nicotine levels to be certain they are not smoking prior to surgery. The reality is that very few actively smoking patients are able to quit. I offer smokers breast reconstruction with muscle-sparing free TRAM flaps to maximize the perfusion and reliability of the flap. I do not plan to use DIEP or SIEA flaps on active smokers.

Previous abdominoplasty is an absolute contraindication for breast reconstruction with lower abdominal free flaps, including the SIEA flap. I consider previous abdominal liposuction to be a contraindication for breast reconstruction with an SIEA or DIEP flap; however, I have used muscle-sparing free TRAM flaps for breast reconstruction in patients who have had previous abdominal liposuction.