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Medical alert
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Peripheral vascular disease (PVD), also known as peripheral
artery disease (PAD) or peripheral artery occlusive disease
(PAOD), includes all diseases caused by the obstruction of
large arteries in the arms and legs. PVD can result from
atherosclerosis, inflammatory processes leading to stenosis,
an embolism or thrombus formation. It causes either acute or
chronic ischemia (lack of blood supply), typically of the
legs
Classification
Peripheral artery occlusive disease is commonly divided in
the Fontaine stages, introduced by Dr Ren้ Fontaine in 1954.
I: mild pain on walking ("claudication");
II: severe pain on walking relatively shorter distances
(intermittent claudication);
III: pain while resting (rest pain);
IV: tissue loss (gangrene);
Symptoms
Claudication - pain, weakness, numbness, or cramping in
muscles due to decreased blood flow
Sores, wounds, or ulcers that heal slowly or not at all
Noticeable change in color (blueness or paleness) or
temperature (coolness) when compared to the other limb
Diminished hair and nail growth on affected limb and digits.
Causes
Smoking - tobacco use in any form is the single most
important modifiable cause of PVD internationally. Smokers
have up to a tenfold increase in relative risk for PVD in a
dose-related effect. Exposure to second-hand smoke from
environmental exposure has also been shown to promote
changes in blood vessel lining (endothelium) which is a
precursor to atherosclerosis.
Diabetes mellitus - between two and four times increased
risk of PVD by causing endothelial and smooth muscle cell
dysfunction in peripheral arteries. Diabetics account for up
to 70% of nontraumatic amputations performed, and a known
diabetic who smokes runs an approximately 30% risk of
amputation within 5 years.
Dyslipidemia - elevation of total cholesterol, LDL
cholesterol, and triglyceride levels each have been
correlated with accelerated PVD. Correction of dyslipidemia
by diet and/or medication is associated with a major
improvement in short-term rates of heart attack and stroke.
This benefit is gained even though current evidence does not
demonstrate a major reversal of peripheral and/or coronary
atherosclerosis.
Hypertension - elevated blood pressure is correlated with an
increase in the risk of developing PVD, as well as in
associated coronary and cerebrovascular events (heart attack
and stroke).
Other risk factors which are being studied include levels of
various inflammatory mediators such as C-reactive protein,
homocysteine, and fibrinogen.
Risk of PVD also increases if the patient is: over the age
of 50, African American, male, obese, or has a personal
history of vascular disease, heart attack, or stroke.
Diagnosis
Upon suspicion of PVD, the first-line study is the ankle
brachial pressure index (ABPI/ABI) which is a measure of the
fall in blood pressure in the arteries supplying the legs. A
reduced ABPI (less than 0.9) is consistent with PVD. Values
of ABPI below 0.8 indicate moderate disease and below 0.5
severe disease. It is possible for conditions which stiffen
the vessel walls (such as calcifications that occur in the
setting of chronic diabetes) to produce incorrect readings
and high values(>1.3), meriting further investigation
regardless.
If ABPI's are abnormal the next step is generally a lower
limb doppler ultrasound examination to look at site and
extent of atherosclerosis at the femoral artery. Other
imaging can be performed by angiography, where a catheter is
inserted into the femoral artery and selectively guided to
the artery in question and then used to inject radiodense
contrast agent whilst an X-ray is taken. Any stenosis of the
arteries can be identified and treated at the same time by
balloon angioplasty if the stenosis is over a short segment
(<3 cm). However if the artery is occluded or there is
diffuse disease present, then arterial bypass surgery may be
required.
Modern multislice computerized tomography (CT) scanners
provide direct imaging of the arterial system as an
alternative to angiography. CT provides complete evaluation
of the aorta and lower limb arteries without the need for an
angiogram's arterial injection of contrast agent.
Prevalence and Incidence
The prevalence of peripheral vascular disease in people aged
over 55 years is 10%25% and increases with age; 70%80% of
affected individuals are asymptomatic; only a minority ever
require revascularisation or amputation.
In the USA peripheral arterial disease affects 12-20 percent
of Americans age 65 and older. Despite its prevalence and
cardiovascular risk implications, only 25 percent of PAD
patients are undergoing treatment.
The incidence of symptomatic PVD increases with age, from
about 0.3% per year for men aged 4055 years to about 1% per
year for men aged over 75 years. The prevalence of PVD
varies considerably depending on how PAD is defined, and the
age of the population being studied. Diagnosis is critical,
as people with PAD have a four to five times higher risk of
heart attack or stroke.
In Western Australia, the prevalence of symptomatic disease
at around 60 years of age is about 5%.
A study from the NHANES 19992000 data found that PVD
affects approximately 5 million adults.
The Diabetes Control and Complications Trial and U.K.
Prospective Diabetes Study trials in people with type 1 and
type 2 diabetes, respectively, demonstrated that glycemic
control is more strongly associated with microvascular
disease than macrovascular disease. It may be that
pathologic changes occurring in small vessels are more
sensitive to chronically elevated glucose levels than is
atherosclerosis occurring in larger arteries.
Therapy
Dependent on the severity of the disease, the following
steps can be taken:
Conservative measures include Smoking cessation (cigarettes
promote PVD and are a risk factor for cardiovascular
disease). Regular exercise for those with claudication helps
open up alternative small vessels (collateral flow) and the
limitation in walking often improves. Medication with
aspirin, clopidogrel and statins, which reduce clot
formation and cholesterol levels, respectively, can help
with disease progression and address the other
cardiovascular risks that the patient is likely to have.
Treadmill exercise has been reviewed as another treatment
with a number of positive outcomes including reduction in
cardiovascular events and improved quality of life.
Angioplasty (PTA or percutaneous transluminal angioplasty)
can be done on solitary lesions in large arteries, such as
the femoral artery.
Plaque excision, in which the plaque is scraped off of the
inside of the vessel wall.
Occasionally, bypass grafting is needed to circumvent a
seriously stenosed area of the arterial vasculature.
Generally, the saphenous vein is used, although artificial
(Gore-Tex) material is often used for large tracts when the
veins are of lesser quality.
Rarely, sympathectomy is used - removing the nerves that
make arteries contract, effectively leading to
vasodilatation.
When gangrene of toes has set in, amputation is often a last
resort to stop infected dying tissues from causing
septicemia.
Arterial thrombosis or embolism has a dismal prognosis, but
is occasionally treated successfully with thrombolysis.
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