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It is relatively rare for atherosclerosis to affect
the upper extremities and cause symptoms. Even diabetic patients, who are frequently
affected by circulation disturbances of the legs, are rarely troubled by occlusion
of the arteries to the upper extremities. The reason for the sparing of the upper
extremities from arterial occlusive problems is not entirely clear, but it is a
well-documented observation. Having said that, there are a few exceptions. Atherosclerotic
occlusive disease of the subclavian artery is seen and occasionally will cause pain
in the upper extremities. This pain is typically brought on by exercise and especially
with repetitive movements of the upper extremity such as brushing one's hair. For
reasons that again are unclear, it is more common for the atherosclerotic plaque
to accumulate on the left side than it is on the right side. An examining physician
may be alerted to this phenomenon by a difference in the quality of the pulse between
the left wrist and the right wrist. The pulse on the left side may appear weaker
and this can be confirmed by measuring the blood pressure in both upper extremities.
It is common enough for older individuals to have a difference in the blood pressure
of their arms that it is a worthwhile test for a physician to check the blood pressure
in both upper extremities to be certain that there is not a difference between the
two sides. If in fact, there is a difference between the blood pressure in the right
and left upper extremity, the arm with the higher blood pressure is considered the
accurate blood pressure for that individual. As mentioned, it is rare for patients
to actually notice that they have atherosclerotic occlusive disease affecting the
upper extremities and most of the time this relatively uncommon condition goes unrecognized.
In certain instances, however, repetitive exercise of the left upper extremity can
cause not only pain in the left arm but also dizziness and, in fact, patients have
been known to actually faint. This condition is called "subclavian
steal syndrome". The anatomical situation is one in which there is a build-up
of atherosclerotic plaque in the subclavian artery on the left side with decreased
flow to the left arm. With exercise, the left upper extremity can actually "steal"
blood from the brain through the vertebral artery by causing a reversal of blood
flow from the brain and down into the left arm. This can result in "syncope".
The diagnosis is suspected by the history and confirmed by the finding of a markedly
decreased blood pressure in the left upper extremity compared to the right side
and further confirmed by noninvasive testing and ultimately by angiography. Treatment
is readily available for this condition and consists of revascularizing the left
upper extremity by either balloon angioplasty/stenting
or surgical bypass from the carotid artery to the subclavian artery (carotid-subclavian
bypass), which is a very durable procedure and serves to restore the circulation
to the left arm and eliminate the risk of syncope.
Finally, upper extremity arterial insufficiency can be caused by emboli. In this
situation, clots can form on the heart valves or in the "great vessels" leading
out of the heart (such as the aorta or subclavian arteries) and this can lead to
particles of cholesterol debris or blood clot moving "downstream" into the arteries
of the arms or hands and causing an acute decrease in circulation. This acute interruption
of blood flow can sometimes create an urgent situation requiring surgical intervention.
Surgical treatment is usually highly effective in removing the emboli and restoring
circulation. Efforts must be made to identify the source of the emboli however,
so that recurrence of the emboli can be prevented. Patients will typically undergo
transthoracic echocardiography or transesophageal echocardiography
and occasionally may need a formal angiogram to assess the arteries in the chest,
which lead from the heart to the upper extremities.