Initial preparations

In the operating room the patient is placed in the supine position, with the arms tucked close to the patient’s torso, to allow for easier access of the microscope to the recipient vessels. Loupe magnification ×5.5 is used throughout the harvest of the flap while microscope magnification is used for the vessel anastomosis. We do not inject any local anesthetic or vasoconstrictors at donor or recipient sites.

Flap harvest (Figs 10.3a–b and 10.6b)

The SIEA flap harvest is initiated by carefully incising the inferior aspect of the abdominal flap, at this stage just deeper to the dermis, starting on the ipsilateral side of the reconstructed breast. The subcutaneous dissection is carefully performed, as not to injure the SIEV which is frequently quite superficial. The SIEA and SIEV are identified and separated from the surrounding tissue. The SIEA is then preserved with vessel loops and explored at the lower line of skin incision.

We have previously published our algorithm for choosing the SIEA flap in breast reconstruction.⁷ In this review of our clinical experience with the SIEA flap, we have noted that whenever the diameter of the SIEA was smaller than 1.5 mm as the pedicle entered the flap (lower line of abdominal incision), there exists an increased chance of vascular compromise. Thus, when opting to use the SIEA flap we precede in the following manner; using a vessel sizer provided with the venous coupler, we measure the SIEA’s external diameter; if its external diameter is larger than 1.5 mm and there is a visible, palpable and audible Doppler pulse, the artery and its venae comitantes are dissected in a retrograde fashion. We do not necessarily dissect the vessels to their origin; rather we continue the dissection as long as we can perceive an increase in the vessel diameter. Once a point is reached at which the diameter is constant there is no need for further dissection since pedicle length is rarely an issue with SIEA flaps (contrary to DIEP flaps). Another key point to keep in mind during pedicle dissection is not to skeletonize the vessels. Preferably a narrow cuff of tissue (e.g., fat) is left just deep to the vessels to protect the vascular pedicle. One should refrain from adding too much surrounding tissue that could unnecessarily lead to prolonged seroma formation due to removal of lymphatic nodes and ducts. Only the distalmost part of the vessels is fully skeletonized, at the area closest to the anastomotic site.

Additionally, in cases in which the SIEA is borderline in caliber, we also look at the SIEV caliber before making the final decision between the SIEA and DIEP flaps. When a sizable SIEV is present we assume dominance of the superficial draining system and strongly consider using the SIEA flap, and not the DIEP flap, despite a non-remarkable SIEA caliber.

Since we published our original description of the algorithm for choosing the SIEA flap⁷ we have changed our preferred hemi-abdomen for unilateral reconstructions, and are now preferentially using the ipsilateral side. The rationale for preferring an ipsilateral flap is threefold. First, the SIEA pedicle enters the abdominal flap on its lateral aspect (usually lateral to the lateral row of the DIEA perforators), thus, since the flaps are rotated 180° for their final inset, vessel proximity to the recipient internal mammary vessels is preferable in ipsilateral flaps. Second, the final positioning of the least reliable zone of blood supply (across the midline) will be at the lateral aspect of the reconstructed breast and not medially (should there be any flap loss preferably it should be laterally). Lastly, suturing of the flap at the previous umbilical excision site will cone and shape the breast at the desired position laterally. In unilateral cases both SIEA’s are explored before making the final decision as to the preferred pedicle side which is mainly based on arterial caliber.

Naturally, in unilateral cases where the ipsilateral external diameter is smaller than 1.5 mm or the pulse is weak, we explore the contralateral SIEA. If the contralateral SIEA is adequate, we preserve it and use the contralateral SIEA flap. If, however, both superficial systems are too small or display a weak pulse at the level of the lower abdominal incision we assume a dominance of the deep perforator system and revert to the use of DIEP flaps. As in the SIEA flaps, also in DIEP flaps, preference is given to the ipsilateral side. The lateral perforator row is explored followed by the medial row on the ipsilateral side, if inadequate; the contralateral side perforators are then analyzed.

In bilateral cases the selection criteria are similar and dictate the use of an ipsilateral SIEA flap or an ipsilateral DIEP flap. One should keep in mind that a combination of SIEA flap for one side and a DIEP flap for the other is a rational alternative, when taking into account the reduced donor site morbidity compared to bilateral DIEP or free TRAM flaps.

Once the SIEA flap has been chosen, and the vessels are preserved, we progress quite rapidly with the dissection. In the majority of cases the upper incision line starts at the ASIS and extends to just above the umbilicus on each hemi-abdomen. The incision is deepened down through the adipose tissue to the loose areolar tissue plane above the abdominal muscular fascia. The flap is elevated from lateral to medial, using Bovie cautery to ensure meticulous hemostasis is obtained, thus not obscuring accurate surgical planes, making it easier not to incise any fascia.

Next, the umbilicus is delivered from the surrounding flap tissue; with the aid of two skin hooks to elevate the umbilicus, a circumumbilical incision is performed and carried down to the rectus sheath plane. One should make sure enough blood supply is maintained with the umbilical stalk by avoiding the skeletonization of the umbilical stalk. The abdominal flap is then dissected apart from the umbilicus. It is essential at this stage to be alert to the possible existence of periumbilical hernias, which should be noted and repaired at the abdominal closure stage.

As previously mentioned special consideration should be given to unilateral reconstructions regarding the amount of abdominal tissue needed to match the contralateral side. In cases where more tissue is needed than can be obtained from a hemi-flap, we will still consider using the SIEA flap because in the majority of cases the SIEA flap perfusion is reliable across the midline up to the lateral row of the contralateral deep perforators. In our experience with more than one hundred SIEA flaps we have not encountered increased incidences of fat necrosis (partial flap loss) using this guideline. More so, upon reviewing the patient data base we have recognized that the average percentage of flap used was 66.5% of the total abdominal tissue available (zones I to IV). It is our observation that as long as zone IV and any poorly perfused zone III tissue are excised while the flap is perfused by its vascular pedicle at the donor site, we do not have to define the limit of the flap at the midline or in terms of its weight.

If concern still exists regarding reliable perfusion of the SIEA flap we will test the ability of the superficial system to support the flap while still having the option to revert to a DIEP flap. To accomplish this, we maintain two to three perforators from the ipsilateral deep system, and then we simply clamp any deep perforator encountered and the contralateral SIEA and SIEV (if still not ligated) with vascular clamps, thus maintaining flap perfusion solely on the ipsilateral superficial system. We then visually assess the flap for signs of poor perfusion.

Using this simple test, in cases where resection of the underperfused tissue will not leave enough flap tissue for reconstruction, we have not ‘burnt the bridge’ of using the deep perforator system, which is more likely to support more tissue across the midline.

When reconstructing bilateral cases the abdominal tissue is split along the midline into two hemi-flaps of similar size. After completing the anastomosis of the first side attention is then turned to the superficial inferior epigastric vein and artery of the second side. Once more, as in the first side the vessels are examined for their adequacy according to the previously described criteria, and the algorithm for choosing the SIEA is implemented once more. We have performed many bilateral reconstructive cases in which one flap was based on the superficial system while its counterpart was based on the deep perforating system. This type of reconstruction has the advantage of not compromising the abdominal fascia on both sides compared to a bilateral DIEP or bilateral free TRAM.

After complete elevation of the flap from the abdominal wall (still attached to the vascular pedicle) we will mark the superficial aspect of the vascular pedicle for future reference. The flap edges are then stapled back into place and attention is turned to the mastectomy defects.

Managing the mastectomy skin

We can usually obtain the best cosmetic results in patients who undergo skin-sparing mastectomy with immediate reconstruction, since the flap merely serves as a neo-filler for the recently emptied skin envelope. We also fabricate a small skin paddle, which will serve as the platform for nipple reconstruction and the area to be tattooed as the areola after the flap has healed.

As previously mentioned, in cases in which irradiation is part of the treatment regimen, we will defer reconstruction to 6 months after completion of treatment and will opt for delayed reconstruction. When confronted with delayed reconstruction, depending on the type of mastectomy performed and whether or not the mastectomy skin had been irradiated, one could potentially encounter a few reconstructive scenarios. In cases when a skin-sparing mastectomy was performed and no irradiation was given or the skin changes after irradiation are judged to be minimal, we will attempt to raise the mastectomy skin flaps and use them as the skin envelope for the flap. If, however, not enough skin is left to recreate the skin envelope (as in a simple mastectomy) and/or there are noticeable skin irradiation changes, we usually prefer to remove the skin below the mastectomy scar, leaving any subcutaneous tissue as an additional layer under the flap and over the chest wall. We will then use a bigger skin paddle to reconstruct most of the missing skin envelope.

In both immediate and delayed reconstructions the height and integrity of the IMF is revised, and the lateral border of the breast pocket is re-created by interrupted sutures as needed. Since the upper abdominal tissue will inevitably be pulled downward to close the abdominal donor site, it will tend to pull the chest skin along. It is important to consider this and to compensate accordingly by adequately positioning the IMF, in certain cases even raising the IMF by 1–2 cm.

Recipient site vessel dissection

The internal mammary vessels are the recipient vessels of choice in the vast majority of our reconstructive cases. Secondary options include the internal mammary perforator vessels, serratus perforators, and thoracoacromial vessels. Rarely, we have found the need to perform a contralateral (e.g., crossover) anastomosis. We refrain from using the thoracodorsal pedicle, because it serves as the nourishing vessels for a latissimus dorsi flap reconstruction in cases of a failed free flap.

Depending on the palpated width of the intercostal space either the second or third intercostal space is chosen. If indicated, though rarely, we will resect a part of the rib costochondrium using a rongeur to widen the intercostal space.

Next, a small slip of the pectoralis muscle is elevated, excised, and sent to pathology. The underlying intercostal muscles are cautiously exposed, and resected to reveal the underlying internal mammary artery and vein.

Loupe magnification and microsurgical instruments are used to prepare the artery and vein for the microanastomosis. At this stage we compare the recipient vessel diameter to the SIEA (in the majority of cases the internal mammary artery (IMA) to the SIEA). If an arterial size discrepancy greater than 0.5 mm exists between the recipient vessel and the SIEA, we strongly consider reverting to a DIEP flap.

Vessel anastomosis

The mastectomy skin is gently retracted to provide adequate exposure of the internal mammary vessels for anastomosis. Now, under microscope magnification the internal mammary vessels are definitively primed for anastomosis.

Once the internal mammary vessels are prepared, the SIEA, venae comitantes, and SIEV are ligated and the flap is brought up to the ipsilateral mastectomy field (depending on the adequacy of the ipsilateral side). The flap is turned 180° and appropriately positioned for anastomosis. The flap is then stapled to the surrounding skin, having the SIEA vessels align with the internal mammary artery and vein, and covered with a moist laparotomy sponge. Next the distal part of the IMA and internal mammary vein (IMV) are ligated as distally as possible leaving enough length for comfortable positioning of vascular clamps.

Most often we will begin with the venous anastomosis of the IMV and the SIEA venae comitantes by using an appropriately measured coupling device. Depending on the caliber and length of the veins one can choose between the medial or lateral IMV. We have found that the medial IMV is more commonly used since it is a better size match (wider caliber) to the venae comitantes. However, when the medial and lateral veins are similar in caliber we will prefer to use the lateral IMV since it tends to be longer. Preferably the venae comitantes were harvested distal to their point of merging; hence the anastomosis is completed to the merged vessel.

Although initially we used to anastomose the IMV to the SIEV, we have abandoned this technique and routinely anastomose to the venae comitantes. We have found that both the vessel caliber and the proximity of the venae comitantes, which naturally accompany the artery (as apposed to the SIEV that exits the flap in a less favorable orientation) are anatomically more convenient and carry a lower risk of vessel kinking compared to when we utilized the SIEV. Hence to date we reserve the SIEV primarily for cases in which the venae comitantes are inadequate or a second backup venous anastomosis is needed (rarely a problem with SIEA flaps that typically have excellent venous drainage).

Subsequently the IMA and SIEA ends are brought into proximity with a double opposing clamp for the arterial anastomosis which is completed in standard fashion using a running or interrupted 9-0 nylon sutures. Upon completion of both vascular anastomoses an internal Doppler cuff is positioned around the venous anastomosis.

Flap inset

Once the anastomosis is complete, attention is turned to the flap inset. Attention should be focused on the way the SIEA pedicle is oriented on the chest wall, and it is at this stage that the previous marking of the superficial side of the pedicle becomes helpful. First, the pedicle should not twist on itself throughout its course into the flap. Second, the SIEA pedicle travels from within the intercostal space and up into the superficial layer of the flap, this causes a steep curvature (step off) over the chest wall and pectoralis major muscle. Ensure the pedicle is not kinked or compressed under the flap at this point. Moreover, when the overlying skin has been irradiated, there is a higher likelihood of increased skin tension on the flap and the more superficial location of the SIEA pedicle. Every effort should be made to properly orient the pedicle at this critical stage, the appropriate time should be taken to re-explore any change in the internal Doppler signal prior to making the final flap inset. Interrupted 2-0 Monocryl^™ sutures are positioned between the flap and chest wall usually on the superior–lateral and inferior aspects to anchor the flap in position.

During the final stages of flap inset the patient’s bed is flexed into the semi-sitting position. This is done to assess the final positioning of the reconstructed breast on the chest wall, check for breast symmetry and aid in the abdominal donor site closure. It is also of paramount importance to check for any changes in Doppler signals while the patient is seated.

Skin paddle design (Fig. 10.3c)

The skin paddle is designed to compensate for the resected mastectomy skin, while the rest of the surrounding skin is de-epithelialized. In skin sparing mastectomies an island of skin should be enough to replace the nipple–areola complex, while in more aggressive mastectomies a more prominent skin paddle will be needed to reconstruct the skin envelope. In delayed reconstruction of non-skin-sparing mastectomies almost all the skin of the SIEA flap will be utilized for reconstruction.

Prior to skin closure, two 15F Blake drains are placed in each breast, one inferior, the other lateral, cutting them short enough as not to reach the anastomotic site. The skin is closed in layers, subcutaneous/deep dermis with interrupted 3-0 Monocryl^™, and subcuticular running 4-0 Monocryl^™, burying the suture ends. Finally a skin adhesive is placed over the wound edges. We avoid the use of any Steri-strips or tape that might bruise the skin once the inevitable flap swelling takes place.

Abdominal closure

Naturally in the SIEA flap the rectus fascia does not need to be closed. However, in cases in which a rectus diastasis was noted prior to surgery, and also confirmed intraoperatively, we will plicate the rectus fascia above and below the umbilicus. If, however, a DIEP flap was used, we will suture the rectus fascia with interrupted Ethibond^™ sutures.

After meticulous hemostasis is achieved, the neo-umbilical site on the abdominal wall is marked and the umbilicus is delivered in standard surgical fashion. It is sutured in place using 3-0 and 4-0 interrupted Monocryl^™ sutures.

Two 15F Blake drains are placed in the abdominal donor site, each exiting through the lateral edge of the incision. The abdomen is closed in multiple layers; Scarpa’s fascia first using interrupted 2-0 Monocryl^™, followed by deep subcutaneous interrupted 3-0 Monocryl^™, and finally a running subcuticular 4-0 Monocryl^™. The skin edges are finally sealed with skin adhesive, and a dry Kerlix® dressing is laid on top.