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Page 4 of 13 Fisher et al. Plast Aesthet Res 2024;11:36 https://dx.doi.org/10.20517/2347-9264.2024.53

the dorsal sensory ganglia increases significantly, especially if bleeding from the thin-walled venae
comitantes is encountered. Further, at the level that the vascular pedicle must be divided to avoid the risk of
nerve injury associated with dissection in the region of the dorsal sensory ganglia, the caliber of the artery is
[19]
narrow, ranging from 0.8 to 1.2 mm . Finally, to add to the technical challenges of flap harvest, the LAP
venae comitantes are thin-walled and thus can easily tear and bleed.

Pedicle dimensions and the typical size mismatch encountered between the flap artery and the recipient
artery dictate that interposition arterial and venous grafts between the flap pedicle and the recipient vessels
are almost universally beneficial. The use of grafts helps reduce the risk of thrombosis and flap failure [22,23] .
Additionally, a short vascular pedicle [without the use of interposition arteriovenous (AV) grafts] severely
constrains the options for insetting a flap at the chest and potentially compromises the aesthetic outcome of
the reconstruction.

Although the senior author has performed bilateral simultaneous LAP flap breast reconstruction, given the
complexity of the procedure, the potential for prolonged ischemia time for one or both flaps in
simultaneous procedures, and reduced failure rates reported after transitioning from bilateral simultaneous
to staged unilateral procedures, we currently favor the staged approach for patients requiring bilateral LAP
flap breast reconstruction [21,23] .

RELEVANT VASCULAR ANATOMY
The lumbar vasculature most commonly arises from the posterior abdominal aorta as 4 paired vessels .
[9]
These perforators can be musculocutaneous or septocutaneous, and the latter provides the basis for the LAP
flap. The lumbar perforators initially traverse a course between the vertebral bodies and the psoas major
muscles [Figure 1]. The vessels then run posterolaterally between the erector spinae and quadratus
lumborum muscles to pass through the thoracolumbar fascia and enter the subcutaneous tissue
approximately 7 to 10 cm lateral to the posterior midline . Generally, the diameter of the vessels increases
[20]
from L1 to L4 levels. The L4 perforator is frequently the most ideal perforator upon which to base a LAP
flap as these vessels are among the largest in caliber, have septocutanous anatomy, and are found
anatomically superior to the bony pelvis. The L5 perforators are sometimes the largest in diameter; however,
the L5 perforators can be adherent to the pelvic bone and, in such circumstances, are particularly
challenging to dissect .
[8]

Typical lumbar artery diameter is 0.8-1.1 mm, and the associated veins are approximately 2 mm in diameter
at the level at which the pedicle is harvested. We typically find that either DIEP or TD grafts (both artery
and vein), when dissected to length, reasonably match the lumbar flap pedicle with respect to both arterial
and venous diameter. The proximal ends of these grafts match the internal mammary recipient vessels well.

Preoperative imaging to map perforator anatomy is, in our experience, an essential step in planning LAP
flap harvest. Because the perforators that supply the distribution of the LAP flap penetrate the
thoracolumbar fascia approximately 7 cm lateral to the posterior midline, they inherently enter the
subcutaneous fat of the flap beneath a narrow portion of the skin island. It is essential to design the flap to
capture the best perforator(s). Magnetic resonance angiography is the preferred modality as it avoids the
abdominopelvic radiation associated with high-resolution CT angiography, although the disadvantages of
this technique are cost and availability .
[18]