Brief overview
- Symptoms: Seizure-like dizziness, visual disturbances, impaired consciousness, headaches, pain in one arm; especially when the affected arm is moved.
- Causes and risk factors: Constriction in one of the subclavian arteries supplying the arm; “tapping” of the vertebral arteries supplying the brain. Smoking, lack of exercise, high blood fat and vascular disease are risk factors.
- Diagnosis: Symptoms, medical history, blood pressure measurement on both arms, ultrasound with visualization of the blood flow, possibly computer or magnetic resonance imaging, angiography.
- Treatment: Surgery to widen the constriction or bypass it with a bypass.
- Prognosis: treated, good prognosis; untreated, complications up to and including stroke possible.
- Prevention: If the risk is known, blood circulation check-ups; reduce the risk of arteriosclerosis by giving up smoking, healthy eating and exercise.
What is subclavian steal syndrome?
Subclavian steal syndrome is a very rare circulatory disorder of the brain. It occurs when a subclavian artery, which is responsible for the blood supply to the arms, is narrowed. This narrowing is usually caused by calcification of the vessels.
This results in a lack of supply to various parts of the brain. To better understand the causes of subclavian steal syndrome, it is worth taking a brief look at the anatomy.
Anatomy
The brain is supplied with blood by the right and left internal carotid arteries as well as the right and left vertebral arteries. These arteries are connected to each other via intermediate blood vessels.
The left carotid artery originates from the main artery (aorta). The left subclavian artery branches off to the left. The right side of the body is supplied by the brachiocephalic trunk, which originates from the aorta. This then divides into the right subclavian artery and the right carotid artery.
The respective vertebral artery arises from the right and left subclavian artery. This runs along the vertebral bodies towards the skull, where it supplies parts of the brain. The subclavian artery runs further under the collarbone towards the armpit and supplies blood to the arms.
Due to the course of the blood vessels, the carotid artery, vertebral artery and subclavian artery are connected to each other.
Subclavian steal syndrome and subclavian steal phenomenon
This is to be distinguished from the subclavian steal phenomenon. Doctors use this term when the cause of a possible subclavian steal syndrome is present, but the patient does not (yet) show any symptoms, i.e. is asymptomatic.
How does subclavian steal syndrome manifest itself?
Subclavian steal syndrome manifests itself through various symptoms that usually only affect one side of the body. Not all of the following symptoms are always present. Some patients remain symptom-free when the subclavian artery is constricted (asymptomatic, subclavian steal phenomenon).
The following symptoms are typical of subclavian steal syndrome:
- Undirected vertigo (unlike other types of vertigo, the surroundings or the ground do not appear to move in a certain direction)
- Impaired balance, ringing in the ears
- Unsteady gait
- Visual disturbances, eye muscle paralysis
- Disturbances of consciousness up to fainting, sudden falls possible (fall attack)
- Paralysis, sensory disturbances
- Speech and swallowing disorders
- Headaches at the back of the head
In the case of subclavian steal syndrome, the symptoms often worsen when the patient moves the arm on the affected side.
Pain, pallor and reduced temperature of one arm are also possible.
The symptoms occur both permanently (chronically) and in attacks when the affected arm is moved.
The cause of subclavian steal syndrome is a severe narrowing (stenosis) or occlusion of the subclavian artery or the brachiocephalic trunk. The decisive factor here is that this narrowing is located before the vertebral artery leaves the subclavian artery.
The narrowing means that too little blood reaches the arm on the affected side. This creates negative pressure in the subclavian artery. Due to the force of gravity, this taps into the vertebral artery, which normally supplies the brain. The blood flow of the vertebral artery is reversed and the blood flows from it into the subclavian artery and no longer into the brain.
Possible causes of arterial narrowing are arteriosclerosis (narrowing of the vessel due to calcium deposits), a special form of arterial inflammation (Takayasu’s arteritis) or so-called cervical rib syndrome, in which an additional rib on the cervical vertebra narrows blood vessels.
Due to the compensatory or bypass mechanisms in subclavian steal syndrome, there is a lack of blood in the brain. Especially when the affected arm has an increased need for blood, such as during movement, the lack of blood supply to the brain increases. This leads to symptoms such as dizziness or impaired vision, particularly on the affected side.
Risk factors for subclavian steal syndrome
Risk factors for this are smoking, elevated blood lipid levels and lack of exercise. In addition, vascular malformations are a risk factor for constrictions and the rare occurrence of an additional neck rib.
Examinations and diagnosis
Your doctor will use various examination methods to diagnose subclavian steal syndrome. First of all, he will ask you about your medical history (anamnesis). He will ask you the following questions, among others:
- Do you often feel dizzy?
- Does the dizziness occur more often after straining your arms?
- Do you have ringing in the ears?
- Is the dizziness swaying, rotating or non-directional?
- Do you suffer from blood lipids?
- Do you have problems with your heart or blood vessels?
- Do you have sudden fainting spells?
Your doctor will then examine you physically. Among other things, he will feel your pulse and measure your blood pressure. If the pulse is weakened on one side and there is a difference in blood pressure of over 20 mmHg between the two arms (millimeters of mercury = mmHg, unit of measurement for blood pressure), this indicates a possible narrowing of the subclavian artery and therefore subclavian steal syndrome.
Your doctor will also listen to your heart and the surrounding blood vessels. If the subclavian artery is narrowed, the flow noise is altered.
In some cases, the doctor also uses other imaging procedures for diagnosis. These include an X-ray examination of the vessels using computer tomography or magnetic resonance imaging (CT or MRI angiography) or angiography with a contrast agent.
The doctor must rule out aortic arch syndrome, which causes similar symptoms but involves constrictions in several vessels.
Treatment
There are various types of treatment for subclavian steal syndrome. If the symptoms are severe, the patient feels a high level of suffering.
If the doctor has found a severe narrowing or blockage of the subclavian artery in the examinations, an operation is performed. Common procedures are percutaneous transluminal angioplasty (PTA) and the insertion of a bypass.
PTA and bypass
In a percutaneous transluminal angioplasty (PTA), a catheter is advanced through a blood vessel to the narrowing. A balloon is placed there to widen the vessel (balloon dilatation).
A bypass allows a constricted vessel to be bypassed: the bypass, which is often made from the body’s own vessels, is connected to the blood vessel in front of and behind the constriction.
Course of the disease and prognosis
With timely treatment, subclavian steal syndrome has a good prognosis. Not all patients with a narrowing of the subclavian artery show the corresponding symptoms (subclavian steal phenomenon). Over time, however, a slight narrowing often turns into a severe narrowing or even leads to complete occlusion of the vessel.
If arteriosclerosis of the subclavian artery is the cause, similar constrictions or calcifications are also possible in other arteries, which may become life-threatening. For this reason, the doctor will also keep an eye on other vascular sections, such as the coronary arteries.
After a heart attack, bypasses of the coronary arteries are often performed using the internal thoracic artery, which originates from the subclavian artery. If a subclavian steal syndrome, i.e. a narrowing of the subclavian artery, occurs, it is possible that such a bypass may result in a deficient supply to the heart and possibly chest pain.
Prevention
Subclavian steal syndrome can be treated preventively if there are known risks or additional hazards, such as with a coronary artery bypass. The doctor attempts to reduce the risk of a possible occlusion of the subclavian artery. Because this type of vascular constriction often occurs with arteriosclerosis, the doctor recommends, for example, not smoking, eating a low-fat, balanced diet and exercising regularly.
Furthermore, blood circulation is examined in regular check-ups as a precautionary measure if there is a corresponding risk or if the disease has already been overcome once
