Subclavian steal syndrome

Subclavian steal syndrome: description

Subclavian steal syndrome is a very rare circulatory disorder of the brain. It occurs when the clavicle artery (subclavian artery) is narrowed. This narrowing is usually due to a calcification of the vessels. The narrowed clavicle artery taps into the vertebral artery (arteria vertebralis), which actually sends blood into the brain: in other words, the clavicle artery “steals” blood from the vertebral artery and thus from the brain. This leads to a lack of supply of various brain sections. To better understand the causes of a Subclavian Steal syndrome, take a look at the anatomy:

anatomy

The brain is supplied with blood by the right and left internal carotid artery as well as by the right and left vertebral artery. These arteries are connected by interconnected blood vessels.

The left carotid artery arises from the main artery (aorta). Left branches off the left subclavian artery. The right half of the body is supplied by originating from the aorta of the brachiocephalic trunk. This then divides into the right subclavian artery and the right carotid artery.

From the right and left subclavian artery originates the respective vertebral artery. This runs along the vertebral body towards the skull and supplies there parts of the brain. The subclavian artery continues under the clavicle along the axilla and takes over the blood supply to the arms.

Due to the course of the blood vessels, the carotid artery, the vertebral artery and the subclavian artery are in communication with each other.

Subclavian steal syndrome and subclavian steal phenomenon

Subclavian steal syndrome is termed as such when there are various signs of disease occurring simultaneously and interrelated. One then speaks of a symptom complex. 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, that is, is asymptomatic.

Subclavian steal syndrome: symptoms

The subclavian steal syndrome manifests itself by various symptoms, which usually affect only one half of the body. Not all of the following symptoms may be present, and some patients remain symptom free (asymptomatic, subclavian steal phenomenon) in narrowing of the subclavian artery.

The following symptoms are typical of Subclavian steal syndrome:

• undirected dizziness, balance disorders, tinnitus
• Impaired vision, eye muscle paralysis
• Disturbances of consciousness
• Paralysis, sensory disturbances
• Speech, swallowing disorders
• Headache on the back of the head

In a subclavian steal syndrome, the symptoms often increase as the patient moves the arm of the affected side.

Subclavian steal syndrome: causes and risk factors

The cause of Subclavian steal syndrome is a severe narrowing (stenosis) or obstruction (occlusion) of the subclavian artery or brachiocephalic trunk. It is crucial that this narrowing is prior to the departure of the vertebral artery from the subclavian artery. Due to the narrowing, too little blood gets into the arm of the affected side. To ensure blood supply to the arm, the subclavian artery taps the vertebral artery, which usually co-powers the brain. The bloodstream of the vertebral artery is reversed and the blood flows from it into the subclavian artery and no longer into the brain. The narrowing of the subclavian artery is therefore bypassed, in which the arm receives blood via the vertebral artery, which in turn receives blood from the brain via the carotid artery, which in turn is fed from the aorta or the brachiocephalic trunk.

Because of these compensatory or bypassing mechanisms in Subclavian-Steal syndrome, there is no blood in the brain. Especially if the affected arm has an increased need of blood as in exercise, the lack of supply in the brain is amplified. As a result, especially on the affected side, deficits such as dizziness or blurred vision occur.

Risk factors for a subclavian steal syndrome

Patients with vascular disease are at particular risk of subclavian steal syndrome. Especially calcifications (atherosclerosis) cause the blood vessels to constrict. Risk factors for this are smoking, elevated blood lipid levels and lack of exercise. In addition, malformations of the vessels can also lead to a narrowing.

Subclavian steal syndrome: examinations and diagnosis

To diagnose a subclavian steal syndrome, your doctor may use different examination methods. First, he asks you about your medical history (anamnesis). For this he asks you the following questions:

• Do you often feel dizzy?
• Does the dizziness increase after a load on the arms?
• Do you have tinnitus?
• Is dizziness staggering, turning or undirected?
• Do you suffer from blood defatting?
• Do you have problems with the heart or the vessels?

Subsequently, your doctor will examine you physically. Among other things, he feels the pulse and measures the blood pressure. If on one side the pulse is weakened and there is a blood pressure difference of more than 20 mmHg between both arms, this indicates a possible narrowing of the subclavian artery and thus a subclavian steal syndrome.

Your doctor will also listen to your heart and surrounding blood vessels. In a narrowing of the subclavian artery, he can hear there a not normal flow noise.

If you suspect a Subclavian Steal Syndrome, your doctor may arrange for further investigation. The method of first choice is the Doppler or duplex sonography. This is an ultrasound scan that shows both blood vessels and blood flow. Thus, a possible narrowing of the subclavian artery and a reversal of the blood flow in the vertebral artery can be shown.

Other imaging modalities may be used in addition to the diagnosis of subclavian steal syndrome. This includes an X-ray examination of the vessels by means of computed tomography or magnetic resonance tomography (CT or MRI angiography).

Subclavian steal syndrome must be distinguished from aortic arch syndrome, which may produce similar symptoms but may be narrowed in multiple vessels.

Subclavian steal syndrome: treatment

There are several ways to treat Subclavian steal syndrome. If severe symptoms are present, if the patient experiences a high level of suffering, and if the examination reveals a severe narrowing or occlusion of the subclavian artery, an invasive therapy is performed. Invasive surgery is an invasion of the body (such as surgery). Common procedures are percutaneous transluminal angioplasty (PTA) and the insertion of a bypass.

Transluminal angioplasty and bypass

In transluminal angioplasty (PTA), a catheter is advanced through a blood vessel to the narrowing. There, a balloon is placed, which widens the vessel.

A bypass allows the circumvention of a narrowed vessel: The bypass, which often consists of the body’s own vessels, is connected to the blood vessel before and after the narrowing. In this way, the inflowing blood is guided past the bypass at the constriction and the underlying body sections continue to be supplied.

Preventive measures

In addition, the Subclavian Steal Syndrome can be treated preventively. An attempt is made to reduce the risk of possible occlusion of the subclavian artery. Because such a vasoconstriction often arises in arteriosclerosis, it is important to treat or prevent it. Accordingly, you should not smoke, eat a low-fat and balanced diet and exercise regularly.

Subclavian-steal syndrome: disease course and prognosis

With timely treatment, the 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, a slight narrowing can turn into a severe constriction or even lead to closure of the vessel. Other arteries may also have similar constrictions or calcifications that can become life-threatening. Therefore, other vascular sections, such as the coronary arteries, should also be monitored during the course of the procedure.

Coronary artery bypass glands are often made using the internal thoracic artery (Arteria thoracica interna), which arises from the subclavian artery. If there is a subclavian steal syndrome, ie a narrowing of the subclavian artery, such a bypass can therefore lead to a deficiency supply to the heart.

In addition to these symptoms of subclavian-steal syndrome, occlusion of the subclavian artery may also lead to circulatory disorders in the arm. If the brachiocephalic trunk is narrowed it may be next to the Subclavian steal syndrome Give problems in brain care via the carotid artery. These can lead to strokes.