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The symptoms of subclavian steal syndrome are varied and include a persistence of fainting, arm numbness, and vision problems. The syndrome is caused by an abnormality in blood flow through one or both of the subclavian arteries. Given that they are major arteries branching off the heart’s aorta, supplying oxygen and nutrients to both arms and parts of the chest and head, an irregularity in blood supply can manifest in any of these body destinations. Diagnosis and treatment is recommended, especially if it affects brain function.
Oxygenated blood is pumped out of the heart through the aorta. Among its first major arterial branches are the left and right subclavian arteries, so named because they lie just under the clavicle, or collar bone. For a variety of reasons, their blood flow can become constrained. Stenosis, or the narrowing of a blood vessel, as well as an occlusion such as a blood clot, will impede flow. One of the branches of the subclavian artery is the vertebral artery that threads up the neck toward facial organs and the brain. Particularly during exercise of the arms, there is a corresponding decrease in blood delivered to the vertebral artery, and the subclavian artery is said to have “stolen” blood from normal vertebral artery flow.
Sometimes abbreviated “SSS,” subclavian steal syndrome is also called subclavian steal phenomenon or subclavian steal steno-occlusive disease The condition can become a serious complication when the reportioned blood requires a retrograde, or reverse, flow in the vertebral arteries with concomitant drop in vascular pressure. Even worse, if the hemodynamic, or blood flow, requires retrograde supply from both the vertebral and the neck’s carotid arteries, the brain can lose consciousness from the pressure drop. Presyncope, the sensation of dizziness indicating the possibility that fainting is imminent, is one symptom of subclavian steal syndrome.
The most common symptom of subclavian steal syndrome is arm numbness, which can extend to the fingertips. It may also feel as if one arm is more stiff or heavy than the other. Less common is ocular dysfunction. The left and right vertebral arteries join in the skull to form the basilar artery that supplies blood to the brainstem. Additional arterial branches feed the cerebellum, the portion of the brain responsible for automatic muscle coordination in response to gravity and space. Blood deficiency can cause the sudden disappearance of vision and a loss of balance.
One difficulty of subclavian steal syndrome is that its various symptoms are shared by other vascular causes, including the possibility of an extra rib bone or, rarely, Takayasu’s arteritis, a scarring of the heart’s aorta that predominantly affects young Asian women. Diagnostically, Doppler ultrasound can record the pressure wave in the subclavian arteries, but an angiogram map of the suspect blood vessel with injection of a radioscopic substance may be required. Treatment might necessitate expanding the subclavian artery with a structural stent or inflated balloon angioplasty.