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Pedicled TRAM reconstruction does not usually
involve microsurgical technique. The procedure relies on blood flow
originating in the internal mammary artery and flowing to the skin of the
abdomen via the deep superior epigastric artery. To understand the flap
fully, the anatomy is critical.
The blood supply to the skin and subcutaneous
tissue of the lower abdomen is derived primarily from the deep inferior
epigastric artery (DIEA). This vessel arises from the internal iliac artery and
supplies the rectus abdominus muscle. It begins on the undersurface of the
muscle near the pubic bone and sends branches into the muscle and through the
muscle to the overlying fascia and skin (perforator branches). Eventually the
DIEA communicates with the deep superior epigastric artery (DSEA) in the
substance of the rectus muscle. These communicating branches are termed
"choke" vessels. The vessels are depicted in the figure
above.
The DSEA arises from the internal mammary artery
underneath the sternum and then travels in the substance of the rectus muscle
reach in DIEA via the choke vessels. The pedicled TRAM survival depends on
circulation passing from the DSEA to the DIEA and then to perforators overlying
the skin. The longer distance and choke vessel course may make the
pedicled TRAM more unreliable, especially in obese patients and smokers.
The skin island has been divided into 4 zones (Scheflan
and Dinner, 1983) in order to help predict skin survival in TRAM
reconstruction. This is depicted in the figure below. The skin
directly overlying the muscle to be used in the reconstruction is considered
zone 1. The skin over the contra lateral muscle is considered zone 2, while the
skin lateral to the muscle being used is considered zone 3. The skin lateral to
the contra lateral muscle being used is considered zone 4. Zones 3 and 4
are at the lateral ends of the ellipse, with zone 4 tissue being the least
reliable in a pedicled TRAM reconstruction. Zone 4 tissue is often
discarded.
The TRAM flap is usually mobilized on the muscle
contra lateral to the breast requiring reconstruction. The flap can be
rotated 90 to 180 degrees with careful attention paid to not kinking the
vascular inflow pedicle. A subcutaneous tunnel is made from
the abdomen to the breast pocket that can leave a bulging in the chest well
below and toward the midline of the breast being
reconstructed.
The fascial defect left in the abdominal wall is
closed directly or occasionally with synthetic mesh. If a bilateral
reconstruction is performed, synthetic mesh is more likely.
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