The flap or tissue that the breast is made of is the skin and fat of
the lower abdomen. Basically this is the skin and fat that is
between the belly button and the pubic hairline. This is the skin
and fat that is discarded in someone who is having a tummy tuck.
The blood supply to this piece of flesh comes primarily from perforating
blood vessels through the rectus abdominus muscle. These are tiny
vessels that are often about a millimeter in size. These
perforating blood vessels are attached to internal thoracic vessels from
above and to the deep inferior epigastric blood vessels from
below. Obviously the blood vessels that are closer provide the
stronger head of pressure or better blood supply to the
tissue.
For the lower abdominal skin the main blood supply is the deep inferior
epigastric vessels. The perforating vessels from one rectus muscle
primarily supply the skin and fat from that side of the abdomen.
Because of the communication of the blood vessels from one side to the
other some skin on the opposite side of the abdomen will survive on its contralateral
blood supply.
One DIEP flap requires one set of perforators from one rectus muscle
to make one breast. Obviously a bilateral breast reconstruction
requires the perforators from both rectus muscles to make two breasts.
In the DIEP flap the skin, fat, and perforating blood vessels are
separated from the rectus muscle. No rectus muscle is removed.
The rectus muscle is the muscle that primarily supports the
abdomen. It is the main sit up muscle. The entire flap is
isolated on two blood vessels, namely the deep inferior epigastric
artery and vein. These blood vessels are then cut and the flap is
completely unattached to the body. It is positioned on the chest
and then with microsurgery the deep inferior epigastric vessels are sewn
to the internal thoracic blood vessels. In such fashion blood
supply and life is reestablished to this flap.
A living breast is created. Interestingly, the body doesn't
recognize that this piece of abdominal tissue is in a different
location. If the person with a DIEP flap reconstruction were to
gain weight and the weight that this person gained always went to the
abdomen before the surgery, then the breast will get larger. The
opposite of this is also true.
