tones and strengthens the muscles of the legs,
which then can help to support the veins. The
rhythmic movement of the leg muscles during
walking also helps push blood through the veins.
Treatment for severe varicose veins may
include sclerotherapy, in which the doctor injects
a chemical into the varicose vein that causes the
vein to SCARand close. Blood reroutes to other
veins, and the varicose vein gradually shrinks and
fades to become barely noticeable. LASER SURGERY
is effective on smaller varicose veins. For large
varicose veins that generate significant PAINor are
causing skin ulcers, the doctor may surgically
remove the affected veins in a procedure com-
monly called vein stripping.
The main complication of varicose veins is DEEP
VEIN THROMBOSIS(DVT), in which blood clots form in
the pooled or slow-moving blood. The clots cause
localized pain and swelling, and if they break free
can lodge in the LUNGS, causing PULMONARY
EMBOLISM, or in the BRAIN, causing STROKE. Preven-
tive measures include frequent walking, wearing
low-heeled shoes (which exercise the muscles in
the lower leg), shifting the weight from leg to leg
and rocking slightly back and forth when standing
is necessary, and resting with the legs elevated.
See also HEMORRHOIDS; PLASTIC SURGERY; TELANGI-
ECTASIS; WALKING FOR FITNESS; WEIGHT LOSS AND
WEIGHT MANAGEMENT.
vein A blood vessel that carries BLOOD to the
HEART. All veins except thePULMONARY VEINScarry
deoxygenated blood; the pulmonary veins return
oxygenated blood to the heart from the LUNGS.
Because veins lack the muscular structure and
contractile capability of arteries, they have valves
that keep blood moving only in one direction,
toward the heart. The body’s largest veins are the
superiorVENA CAVA and the inferior vena cava,
which empty blood into the heart’s right atrium.
For further discussion of the veins within the
context of cardiovascular structure and function
please see the overview section “The Cardiovascu-
lar System.”
See also ARTERY.
vena cava The body’s largest veins, which return
deoxygenated BLOODto the HEART. The superior
vena cava brings blood from the upper body and
enters the top of the right atrium. The inferior
vena cava brings blood from the lower body and
enters the bottom of the right atrium. A valve at
the juncture of the inferior vena cava and the
right atrium, called the eustachian valve, prevents
gravity from pulling blood back into the inferior
vena cava.
For further discussion of the superior vena cava
and the inferior vena cava within the context of
cardiovascular structure and function please see
the overview section “The Cardiovascular System.”
See also AORTA; PULMONARY ARTERIES; PULMONARY
VEINS.venous insufficiency A chronic condition in
which the veins cannot adequately return BLOOD
to the HEART, usually as a consequence of defective
valves that allow blood to leak back and pool in
the veins. Some people do not have valves in their
veins, a circumstance that is a CONGENITAL ANOMALY.
Venous insufficiency primarily affects the veins in
the legs, especially the lower legs, and may
accompany or contribute to VARICOSE VEINS. Symp-
toms include edema and characteristic changes in
SKIN color and texture (lipodermatosclerosis).
Many people who have venous insufficiency
experience discomfort, such as burning or itching,
and cramping in the lower legs, and may have fre-
quent skin ulcers that are slow to heal. The diag-
nostic path may include Doppler ULTRASOUNDor
VENOGRAMto evaluate the flow of blood through
the veins.
Treatment is conservative and supportive to the
extent possible, including compression stockings
to help support the veins and intensify the action
of the leg muscles with walking. Frequent walking
massages the veins, helping move blood upward
toward the heart. Resting with the legs elevated
above the level of the heart counters the effect of
gravity on returning blood flow. Surgery may
become necessary when skin ulcers fail to heal
with treatment, or PAINbecomes intense. Surgical
options include VEIN ligation (commonly called
vein stripping) and vein grafts to reroute blood
around severely damaged veins.
See also DEEP VEIN THROMBOSIS(DVT).venogram A diagnostic procedure to evaluate
the flow of blood in the veins, usually in the legs.venogram 115