Subclavian artery disease is often caused by a buildup of plaque—fat, cholesterol and other substances (also called atherosclerosis)—in one of the subclavian arteries. There are two of these: a right subclavian artery and a left subclavian artery that supply blood to your upper body.
The left subclavian artery branches off of the aorta, which is a large blood vessel that starts at the heart and travels into the abdomen. Another artery branches off the aorta on the right (called the brachiocephalic artery) and divides into the right subclavian artery and the right common carotid artery.
Other causes of subclavian artery disease include:
Only a few signs aid your physician in diagnosing this condition. A lower blood pressure reading when using the arm on the side where the artery is blocked is a strong sign of subclavian artery disease. If your health professional suspects you have a blockage, it is important to have your blood pressure checked in both arms. Any consistent blood pressure difference greater than 20 mm Hg suggests subclavian artery disease.
The presence of a harsh noise heard with a stethoscope over the blood vessel involved can be another sign of disease and obstruction.
If you have subclavian artery disease, the symptoms you experience depend largely on the artery involved and the degree of blockage. Symptoms may reflect a lack of blood flow to the area being supplied, such as:
Some patients don't have symptoms because the body adapts in response to the obstruction and can create new blood vessels that go around the blockage.
When the artery that branches from the subclavian artery and supplies the back of the brain is affected, you may experience symptoms of less blood flow to the back of the brain. You may have dizziness, a hard time walking or poor balance.
Exercising the arm affected by the narrowed subclavian artery causes more blood to be sent to the arm instead of the brain. This is called subclavian steal syndrome. Your health care professional may suspect this syndrome if when using your arms you experience:
Some simple tests may help identify this syndrome.