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Subclavian steal syndrome is a condition in which the artery that normally pumps blood from the heart to the brain becomes constricted or blocked, leading to a reversal in the direction of blood flow. The lack of blood supply to the brain can cause a person to experience dizziness, vision problems, arm numbness, and fainting episodes. Subclavian steal syndrome is usually caused by calcium and cholesterol buildups in the arteries, though blood clots or congenital defects can also lead to problems. In most cases, patients need to undergo surgical procedures to reopen or bypass the affected arteries.
The usual site of blockage or constriction is the left subclavian artery, a branch of the aortic arch that extends upward to the neck. Normally, the subclavian artery supplies blood to a vertebral artery, where it is carried to a system of blood vessels in the brain. In the case of subclavian steal syndrome, a blockage reverses blood flow in the vertebral artery so the brain does not receive a sufficient supply of new blood.
Most people who are diagnosed with this condition have a preexisting condition called atherosclerosis, wherein cholesterol and fat build up and harden in the arteries. A blood clot or direct chest trauma can also constrict and damage the subclavian artery. Rarely, an infant can be born with a congenital defect that isolates the subclavian artery from the rest of the heart and circulatory system, rendering it incapable of receiving and transporting blood.
The most common symptoms of subclavian steal syndrome are blurry vision, dizziness, and nausea. Decreased blood pressure in the upper part of the body can cause the left arm to become numb and reduce an individual's ability to concentrate. It is also possible for a person to faint or have a stroke if the blood supply to the brain is severely restricted.
A cardiovascular doctor can diagnose subclavian steal syndrome by analyzing symptoms and conducting a series of diagnostic imaging tests. Ultrasounds, computerized tomography scans, and chest x-rays can reveal the exact site of a blockage or the extent of artery constriction. After making a diagnosis and identifying the underlying cause, the doctor can determine the best course of treatment. Most cases of subclavian steal syndrome do not respond to medical treatment, and individuals usually need to undergo surgery.
Depending on the type and severity of a blockage, a cardiovascular surgeon may try to manually remove fatty deposits, insert a stent into the damaged artery, or conduct a bypass procedure. When stenting is necessary, the surgeon inserts a hollow tube to make sure the artery maintains its shape. A bypass involves redirecting blood flow around the subclavian artery with a donor or artificial tube. Following treatment, a patient usually needs to limit his or her physical activity and attend regular checkups with a cardiovascular doctor to make sure problems do not return.