A Novel Axillary Artery Cutaneous Artery Perforator Flap for Partial Breast Reconstruction

Introduction

With better understanding of vascular anatomy and mapping of angiosomes and perforasomes, flaps used to fill defects after breast conservation surgery have evolved [1]. Volume replacement of partial mastectomy defects with mini-LD flaps is no more the only available option in the era of perforator flaps [2–7]. Hamdi et al. are credited with the first description of partial breast reconstruction with flaps based on cutaneous perforators, arising from the anterior and posterior intercostal arteries [8, 9]. The lateral intercostal artery perforator (LICAP) has been used for lateral breast defects while anterior intercostal artery perforators (AICAP) have been used effectively in filling defects in the lower central and medial half of the breast. Subsequently, the lateral thoracic artery perforator (LTAP) was described by McCulley S. J. et al., which on its own or as a supplement to the lateral intercostal artery perforator could allow lateral breast defects to be reconstructed [10]. The discovery of these perforators with their versatility to reach various parts of the breast without sacrificing the latissimus dorsi muscle has opened up robust options for breast reconstruction. A novel axillary artery cutaneous artery perforator (AACAP) is described here; it allows replacement of defects of the outer half of the breast by itself or in combination with the LTAP.

Material and Methods

Perforator Discovery

A 48-year-old patient who had undergone neoadjuvant chemotherapy for an upper outer quadrant multifocal disease was planned for breast conservation. The defect was about 8 × 4 cm. An LTAP oriented vertically and parallel to the lateral mammary crease was planned, to fill the defect. While performing axillary dissection, the lateral thoracic artery (LTA) was carefully preserved for later reconstruction. While dissecting along the thoracodorsal pedicle, a robust vessel was noted to be running laterally into the skin of the proposed flap. In this case, the LTA was of a narrow calibre and did not inspire confidence. However, this new branch when traced proximally seemed to arise from the axillary artery and the accompanying vein drained directly into the axillary vein. The flap was lifted after dissecting from lateral to medial side, carefully preserving this new branch with its perforators. The length of this branch allowed for easy mobilisation of the flap into the defect. The LTA was used as well to complement the arterial supply of the flap (Fig. 1).

Fig. 1.

AACAP flap design: A incision marking, B skin incision, C specimen excised, D AACb & LTA identified, E flap harvested, F flap insetting, G on table post-operative picture, h 6 weeks post-op

Subsequent to this chance finding, two cadaveric dissections were carried out, to understand from anatomists about the name of this branch. They confirmed that this was an unnamed cutaneous branch arising from axillary artery directly (Fig. 2).

Fig. 2.

Identification of axilary artery cutaneous branch in a cadaveric dissection of the left axilla: A cadaveric anatomy, B artist’s depiction of cadaveric anatomy

Description of the Perforator

The AACAP arises directly from the third part of the axillary artery, usually about 3–4 cm lateral to the thoracodorsal pedicle. While performing an axillary dissection, this perforator is often sacrificed. It is a robust artery with a calibre of about 2.5–3 mm and is accompanied by an equally robust vein draining into the axillary vein. It travels downwards and laterally, superficial to the intercostobrachial nerve, rarely branching into two and straddling this nerve as it makes its way downwards to pierce the subcutaneous tissue of the infra-axillary area, where it gives off multiple perforators. The area supplied by this vessel includes the redundant skin and subcutaneous tissue forming a tier in the back, which continues anteriorly as a fold in the infra-axillary area. This vessel has a distal length of about 6 cm and gives perforators along its course just as the lateral thoracic artery does. This length provides excellent mobility and allows the flap to reach not just the outer half of the breast, but also the central quadrant (Fig. 3).

Fig. 3.

Axillary dissection (A) with artist’s impression (B) of the same depicting the AACAP in relation to the rest of the neurovascular structures

The AACAP, unlike the LTA, is not prone to inconsistencies in anatomical location and lumen calibre. In the management of bigger breast defects, the AACAP is able to complement the supply of the LTA, often being the dominant supply, thus allowing for a large flap to be harvested, without fear of vascular compromise.

Design of the Flap

The breast lump is marked with the patient sitting up or standing. The lateral mammary crease; the inframammary crease and the anterior, mid and posterior axillary lines are marked. The patient is then made to lie down supine with the hand behind the head. Lateral chest wall perforators are identified and marked with a hand-held Doppler. The LTA is marked first, along the lateral chest wall about 2 cm lateral to the lateral mammary crease and just deep to the lateral border of the pectoralis minor, corresponding to the 2nd rib. As the hand-held probe is moved laterally for about 3–4 cm, the AACAP can be identified, running parallel to the LTA, with barely any pressure on the skin. On tracing this branch downwards, the signal travels effectively along the posterior axillary line for about 3 cm before the signal becomes muffled.

The AACAP flap may be designed in an oblique, transverse or vertical manner depending on its orientation with the lateral mammary crease (Fig. 4). In each of these designs, the perforator will invariably pierce the flap close to the centre of the flap, thereby negating the issue of a narrow angle of perfusion. While this perforator by itself can perfuse the entire flap, contribution from the LTA to the anterior half of the flap can enhance the vascularity of the flap. Besides, the communicating vessels between the suprafascial and subdermal linking vessels running within the flap ensure that the entire flap is well vascularised.

Fig. 4.

Axillary artery perforator flap designs: A vertical, B oblique, C transverse

For the vertically oriented flap, the lateral mammary crease is the anterior margin of the flap and the posterior marking is parallel to it along or anterior to the posterior axillary line. The width would depend on how much of redundant skin and subcutaneous tissue is available and allow for comfortable closure after flap harvest. Usually, a width of 6–7 cm is available and a length of 15–20 cm may be harvested depending on the size of the defect. The lateral mammary crease incision curves upwards towards the hairline crease in the axilla in a lazy-S manner to meet the posterior line and to allow for SLNB or axillary dissection. The posterior line is then curved gently downwards to meet the lateral mammary crease and complete the vertical flap design. This flap can be raised in the supine position.

For the oblique flap, the lateral mammary crease is the anterior border of the flap but midway on the lateral mammary crease, the incision turns superiorly and backwards to reach the back. The remaining flap is then designed keeping the perforator in the centre of the flap. This flap is best harvested in the semi-lateral position, with the back tilted with a sand bag for support.

For the transversely oriented flap, best suited for those with sufficient redundancy in the infra-axillary region, the tier extending from the back to the infra-axillary area is utilised to mark the flap. Ellipsoid flap medially placed on the lateral mammary crease and extending to the posterior axillary line or anterior border of latissimus dorsi, laterally and about 5 cm beyond it, offers a good length of about 20–25 cm. The width would be determined by the redundancy of the skin and 8–10 cm is usually available. Large flaps in this area can be propelled to fill central quadrant defects as well. This flap may be harvested in the supine position or semi-lateral position depending on the length of the flap required. The tumour is excised with margins through the lateral mammary crease incision in laterally placed tumours. The flap inset into the defect can be with skin if the tumour is excised with skin or de-epithelialised if no skin is sacrificed at the time of excision of the tumour.

Results and Discussion

While Taylor and Palmer have contributed immensely to the mapping of perforators in the body, a careful look at existing map will reveal gaps in the number of perforators existing in the infra-axillary area [3]. The best described perforators in the chest wall are the posterior intercostal artery perforators, the internal mammary artery perforators and the thoracodorsal artery perforators. A lot of work has gone into defining angiosomes and functional angiosomes or perforosomes and this has been instrumental in designing robust perforator-based flaps pedicled or free [11]. With more than 350 perforators identified so far, a wide variety of perforator-based flaps are possible. The focus for most perforator-based flaps has been the abdomen, the trunk or the limbs. In the last decade and half, a lot of interest has been generated in lateral chest wall perforator-based flaps for partial breast reconstruction, with excellent results accruing from the use of LICAP and LTAP flaps in reconstructions of lateral partial breast defects. [8–10] With the discovery of this novel cutaneous branch from the axillary artery, it may not be amiss to state that there is more to be discovered in terms of branches and perforators in the lateral chest wall area. With better mapping of perforators in the body, with dynamic 4-D computed tomography angiography, it may not be long before we learn more about the yet unmapped vascular territories in this area.

This flap will be a great tool in the armamentarium of breast oncosurgeons. The advantages of AACAP flaps are-

• i)The long length of the vessel which allows for greater flap mobility.
• ii)Versatility of flap orientation, i.e. oblique, vertical or transverse orientations.
• iii)LTAP running parallel to this vessel can augment it and allow for larger flaps to be harvested without vascular compromise.
• iv)Flaps placed lower in a transverse orientation can be complemented by LICAP.
• v)The consistent presence of this vessel makes it a robust alternative to LTAP which may be absent or deficient in 15–20% cases.

Conclusion

AACAP flap is a workable, reliable and easily reproducible technique for lateral and central breast reconstructions. It is an attractive option due to the variable orientation, reduced potential morbidity and the fact that it allows to preserve future reconstructive options.

Declarations

Conflict of Interest

The authors declare no competing interests.