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Inchauste. Plast Aesthet Res 2023;10:27 https://dx.doi.org/10.20517/2347-9264.2022.139 Page 5 of 15

End-to-end anastomosis remains the standard technique for microsurgical autologous free flap breast
reconstruction. This is especially true in the case of more novice microsurgeons, as this provides the best
visualization of the vessel lumen and most pedicle freedom. When end-to-end and end-to-side were
compared, rates of anastomotic thrombosis and flap failure were not significantly different [26-28] . Surgeon
preference and experience with each technique play a role in selection. End-to-end anastomosis does allow
for more freedom of rotation with flap positioning and inset. End-to-side anastomosis can create a tether
point at the anastomosis, which may be a point of possible avulsion injury. End-to-side can be technically
more difficult but allows for continuity of the recipient vessel and maintains distal perfusion.

Some authors describe the use of end-to-side microvascular anastomosis when a significant vessel caliber
mismatch exists. When SIEA flaps are used for autologous free flap breast reconstruction, the superficial
inferior epigastric artery diameter is smaller, usually less than 1.5 mm. This can be less than 50% the
diameter of recipient IM artery, creating a significant size mismatch. The use of either end-to-side
microvascular anastomosis or the use of the thoracodorsal artery as an alternative for a better size match has
been described .
[29]
Internal mammary perforators or end-to-side anastomoses have been described to preserve the internal
mammary vessels [30-32] . The use of internal mammary perforators is limited by the size of the perforators and
[32]
is found to be adequate in less than 10% of cases . Internal mammary perforators have limited use due to
their small size and risk of kinking, therefore, should be reserved for use by experienced microsurgeons.
End-to-side anastomosis for the internal mammary vessels can be considered in cases when preservation of
distal perfusion is desired, such as in patients with coronary artery disease. This allows preservation of the
internal mammary artery for coronary artery bypass grafting [31,33] .

Vessel selection:

One of the key elements of successful microvascular anastomosis is the appropriate selection of the recipient
artery and vein. The thoracodorsal vessels were the first described recipient chest vessels for free flap breast
reconstruction . In early autologous free flap breast reconstruction, axillary lymph node dissection was
[34]
more common, so surgeons routinely used thoracodorsal vessels due to the ease of access within the
operative field. Innovations in breast cancer surgery meant more sentinel lymph node biopsy and less
frequent axillary lymph node dissection. This influenced a change in recipient vessel selection to the internal
mammary (IM) vessels. By contrast, thoracodorsal vessels had a higher rate of conversion compared to
internal mammary vessels in autologous free flap breast reconstruction patients . History of axillary lymph
[35]
node dissection and preoperative radiation were significantly associated with thoracodorsal vessel
conversion .
[35]
Currently, the internal mammary vessels are the predominant recipient vessel of choice due to their larger
size, need for shorter pedicle length, better access for microvascular anastomosis and more central
placement of the flap in the breast pocket [35-38] . The use of internal mammary vessels has also been advocated
because it preserves the thoracodorsal vessels as a backup option for recipient vessels in salvage
reconstruction or pedicled myocutaneous latissimus dorsi flap. Dissection of internal mammary vessels does
have some special considerations. It often requires removal of a small segment of rib cartilage for adequate
exposure. During this dissection, there is potential for pneumothorax, given that only a thin layer of pleura
exists between the IM vessels and the lung. Chest wall movement with respiration and radiation fibrosis can
make recipient vessel exposure and microvascular anastomosis more challenging. The IM vessels have been
found to be the largest at the third intercostal space, which is the most common access point.