Anterograde and Retrograde Flow Anastomoses to the Internal Mammary Vessels in the Third Intercostal Space

It is nowadays widely recognized that autologous flaps provide the optimal means for breast reconstruction by maximizing the ability to predictably create a soft, natural-appearing breast that is durable over time. For these reasons, free flaps from the lower abdominal wall have proven to be better than most other techniques.

In this scenario, the deep inferior epigastric artery perforator flap has become the gold standard treatment for microsurgical breast reconstruction. In selected cases, a superficial inferior epigastric artery flap can be another valuable option for an easier and time-sparing reconstruction.

In most cases, unilateral, unipedicle abdominal flaps provide enough tissue to match shape, projection, and volume of the contralateral breast. In selected cases, bilateral double-pedicle flaps guarantee the safe incorporation of all four vascular zones in the flap design to achieve a satisfactory symmetry. This is necessary in patients with a midline abdominal scar or scant abdominal tissue, such as with huge mastectomy defects or large contralateral breast.

In double-pedicle flap breast reconstruction, our choice to anastomose the two pedicles to the recipient vessels is a crossover anastomosis. This technique has been also defined “turbocharging” by Hamdi et al.[1] It consists in anastomosing the right and left halves of the flap to create a single pedicle for one recipient site. Turbocharging allows for optimal positioning of the flap and avoids two recipient pedicle anastomoses.

Sometimes there is an excessive caliber mismatch between one pedicle and a side branch or the distal end of the contralateral one. In these cases, we prefer to perform two sets of microvascular anastomoses to a single recipient vessel site (Fig. [1]), so as to the proximal and distal end of the internal mammary vessels (IMVs).

Figure 1 The anastomotic configuration: A deep inferior epigastric artery perforator flap pedicle anastomosed to the anterograde flow portion of the internal mammary artery (arrow A) and vein (arrow B), and a superficial epigastric artery flap pedicle to the retrograde flow portion of the same vessels (arrows C and D).

Since its first report by Mu Lan et al, clinical and experimental data have supported the use of the distal segments of the IMVs, which have a demonstrated reliable flow for flap perfusion.[2] [3] The arterial inflow and venous outflow of the distal segments of the IMVs are supplied by their terminal branches. The superior epigastric, the musculophrenic, the intercostals, and the communicating branches to the other IMVs provide for adequate perfusion and venous drainage.

There are potentially adverse situations in which the retrograde flow may be inadequate. Injuries to the superior epigastric or to the intercostal vascular system, or prior use of intercostal artery perforator flaps, should be considered conditions at high risk. In these cases, a multidetector-row computed tomography could help in defining retrograde flow reliability.

We think that retrograde anastomosis is a valuable option not only for double-pedicle flaps but even in cases of unipedicle flap reconstruction. We currently apply this technique as a supplementary venous discharge through a superficial epigastric vein (supercharging)[4] for a congested flap (Fig. [2]). We now consider this site to be our first anastomotic choice whenever a superficial epigastric discharge is needed. We have also used it as a “lifeboat” in a case of iatrogenic damage of the proximal IMV.

Figure 2 A retrograde flow venous anastomosis of a superficial epigastric vein to the distal segment of the internal mammary vein (arrow A). We use it to provide for an added venous outflow in case of congested flaps.

The performance of three to four microvascular anastomoses in close proximity is the main limitation with the use of both proximal and distal segments of the IMVs. The reported solution is to expose a long tract of artery and vein in the widest intercostal space (second or third), with removal of one or more costal cartilage segments.[2] [5]

At our institution, we currently use a rib-sparing technique for IMVs exposure, looking for the vessels in the third intercostal space.[6] This approach usually allows an adequate exposure of recipient vessels for safe and efficient anastomoses, without increasing the risk of complications or operative time when compared with rib-resection technique. Lower pain, for no rib resection, and decreased risk of superomedial thoracic deformities are the main benefits of this method, despite a less comfortable anastomotic procedure.

When using the rib-sparing approach, one concern is that the high number of vessels in close proximity makes the vascular repairs in the interspace at considerable risk for vascular compression. Otherwise, the steeper angle of the pedicle's orientation following anastomosis may result in kinking of the vessels. Our experience and some recently published articles[3] [6] demonstrate that this technique is at no increased risk for vascular compromise.

However, if vessel exposure in the third intercostal space is perceived inadequate for a safe and comfortable anastomosis, a small portion of rib cartilage above or below the interspace should be removed. In our experience, we never need to switch to a full rib-resection procedure.

This technique is relatively easy to perform but does come with a learning curve. It takes some time to get used to performing three to four microvascular anastomoses in a relatively narrow space, with vessels not necessarily on a flat plane. Despite this, we believe that retrograde flow anastomosis should be considered another safe tool in the microsurgeon's repertoire to apply systematically in single-pedicle and double-pedicle abdominal flap breast reconstruction.

REFERENCES

• 1 Hamdi M, Weiler-Mithoff E M, Webster M HC. Deep inferior epigastric perforator flap in breast reconstruction: experience with the first 50 flaps.  Plast Reconstr Surg. 1999;  103 86-95
• 2 Li S, Mu L, Li Y et al.. Breast reconstruction with the free bipedicled inferior TRAM flap by anastomosis to the proximal and distal ends of the internal mammary vessels.  J Reconstr Microsurg. 2002;  18 161-168
• 3 Kerr-Valentic M A, Gottlieb L J, Agarwal J P. The retrograde limb of the internal mammary vein: an additional outflow option in DIEP flap breast reconstruction.  Plast Reconstr Surg. 2009;  124 717-721
• 4 Harashina T, Sone K, Inoue T, Fukuzumi S, Enomoto K. Augmentation of circulation of pedicled transverse rectus abdominis musculocutaneous flaps by microvascular surgery.  Br J Plast Surg. 1987;  40 367-370
• 5 Barabás A G, Shafighi M, Sassoon E M, Haywood R M. The bilateral DIEP flap: a method of bipedicled anastomosis to a single internal mammary artery and venae comitantes.  J Plast Reconstr Aesthet Surg. 2008;  61 1249-1251
• 6 Sacks J M, Chang D W. Rib-sparing internal mammary vessel harvest for microvascular breast reconstruction in 100 consecutive cases.  Plast Reconstr Surg. 2009;  123 1403-1407