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Soft tissue coverage of the hand presents an
ongoing challenge to the reconstructive surgeon. Skin grafts are not always
appropriate, local flaps are not always available, and distant pedicle flaps are
often too morbid. When conservative approaches are not available or have failed
microvascular transplant of an arterialized venous "flow-through" flap
(VFTF) provides a unique and creative option for difficult reconstructions of
the hand.
Musculocutaneous flaps are appropriate for covering
larger soft tissue defects but can be bulky and restrictive when applied to the
wrist, hand, and digits. Fasciocutaneous flaps are thin and pliable. However,
their transplant not only requires sacrifice of a peripheral artery, but can
lead to significant vessel mismatch when anastomosed to distal vessels. In
general, selection of the best flap for a particular reconstruction balances
optimizing form and function at the recipient site with minimizing the morbidity
at the donor site.
Venous flow through flaps (VFTF) are thin and pliable with vessels similar in
size to those of the hand. Their harvest results in minimal donor site
morbidity. These flaps are composed of skin, subcutaneous tissue, and a plexus
of veins. Unlike conventional flaps where the nutrient capillary beds are
supplied by an inflow artery and drained by an outflow vein, the VFTF has no
arterial inflow circuit. All flow proceeds into and out of the flap via the
venous plexus.
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| A venous flap designed on the forearm has two potential
inflow veins on the left and two potential outflow veins. |
The exact physiology of VFTF survival has not been
determined. Three theories have been prosed:
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Reverse Shunting
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Reverse Flow
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Capillary Bypas
In the conventional flap, nutrient capillary beds
are supplied by an inflow artery and are drained by an outflow vein. The
conventional flap tends to be thicker, and is usually well defined in terms of
both inflow and outflow by a named artery and its venae comitans.
While in the venous flap, a vein delivers inflow of blood and outflow of
blood. The flap tends to be thinner, can be designed over numerous
veins, and often does not have a specifically anatomically named inflow and
outflow veinl.
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