LOWER EXTREMITY VASCULAR INSUFFICIENCY
Vascular
insufficiency of the lower extremity is a common finding in the older
population. Factors that increase the risk of vascular disease include diabetes,
obesity, smoking, hypertension, and hypercholesterolemia. Both the venous and
the arterial systems may be affected, and the signs and symptoms are unique to
each. The combination of venous and arterial insufficiency is commonly seen in
older diabetic patients, especially those who smoke. Abnormalities of the lymphatic
system may cause findings similar to those of venous insufficiency. Risk
factors for lymphatic disease include prior surgeries (e.g., inguinal lymph
node dissection), radiotherapy, and idiopathic lymphedema.
Clinical
Findings: Venous insufficiency is a common disease that has no racial or ethnic
predilection. It has been reported to be slightly more common in women. Venous
insufficiency eventually leads to venous stasis and ulcerations. It has been
estimated to be the cause of more than 50% of lower extremity ulcerations, with
arterial insufficiency being the next most common cause, and neuropathic causes
and lymphedema accounting for the remainder.
The first
signs of venous insufficiency may be the development of varicose veins or
smaller dilated reticular veins. As time progresses, venous stasis changes are
seen, including dry, pink to red, eczematous patches with varying amounts of
peripheral pitting edema. Red blood cells are extravasated into the dermis
where, over time, they break down and form hemosiderin deposits, which appear
as brown to reddish macules and patches. Continued venous hypertension, stasis,
and swelling may eventually lead to a venous stasis ulcer. These ulcers are
most commonly present on the medial malleolus region of the ankle but can occur
almost anywhere on the lower extremity. They are usually nontender, but some
can be exquisitely painful. Arterial insufficiency is most often caused by
atherosclerosis of the larger arteries of the lower extremity. Patients often
have coexisting risk factors including older age, hypertension, smoking,
diabetes, and hyper-cholesterolemia. Arterial ulcers are slightly more common
in men, and there is no racial predilection. The clinical presenting signs are
often dependent rubor, claudication, and rest pain. Physical examination
confirms the absence of peripheral pulses in the dorsal pedal and posterior
tibial arteries. At this point, the patient is at high risk for arterial ulcerations
and subsequent gangrene. Surgical intervention is the only viable means of treatment.
Pathogenesis:
Venous
drainage of the lower extremity is accomplished via the superficial and deep
systems of veins that are connected through horizontally arranged communicating
vessels. These veins contain one-way bicuspid valves that prevent backflow and
work with the action of muscle contraction to force the venous flow in a
superior direction, eventually to empty into the inferior vena cava. The flow of
venous blood toward the vena cava is the primary responsibility of the leg
muscles, especially the calf muscle. Patients with sedentary lifestyles are at
higher risk for venous insufficiency. During ambulation, the venous pressure
normally decreases as the blood flow is increased toward the vena cava. If an
abnormality exists and this does not occur, venous hypertension ensues.
Congenital absence of the venous valves, incompetent valves, and a history of
deep venous thrombosis are just three of the potential reasons for venous
insufficiency. Once venous hypertension occurs, the patient is at risk for development of venous
stasis and venous ulcerations.
Arterial
insufficiency is caused by a slow narrowing of the arteries due to cholesterol
plaque. This narrowing restricts the amount of blood flow to the tissue. Once
the flow is decreased to less than the requirement needed for muscle and normal
physiological functioning, symptoms arise.
Histology:
Biopsies
should not be performed in cases of arterial insufficiency, because they lead
to ulcerations, infections, and, most likely, emergent surgery.
Histological
evaluation of venous ulcerations shows a nonspecific ulcer, edema,
proliferation of superficial dermal vessels, and extravasated red blood cells
with a varying amount of hemosiderin deposition.
Treatment:
Venous
insufficiency is treated with a combination of compression and leg elevation.
Losing weight and increasing the activity level may also help. Arterial insufficiency
is best treated surgically with stent placement or arterial bypass of the
narrowed artery. Pentoxifylline has also been used, with variable success, in early disease.
