Subclavian Artery Thrombosis

What is Subclavian Artery Thrombosis?

Subclavian artery thrombosis is a condition where a blood clot forms in the subclavian artery, a large blood vessel in the shoulder area. This clot can considerably lower blood flow to the area that is supplied by the vessel, often affecting the corresponding upper limb. In rare instances, it can also affect the brain and heart. Subclavian artery thrombosis can be a medical emergency if the blood vessel is completely blocked, as it could lead to the loss of a limb or even a stroke if not treated quickly.

People with subclavian artery thrombosis may experience symptoms like pain, numbness, weakness, or coolness in the affected limb, especially during physical activity or when their arm is in certain positions. In severe cases, individuals may notice changes in skin color or even gangrene, which is death of tissue due to lack of blood supply. This condition can be caused by various factors, including atherosclerosis (hardening of the arteries), conditions that make your blood more likely to clot, injury, or certain medical procedures.

Diagnosis involves both a thorough medical evaluation and imaging studies, particularly Doppler ultrasound, computed tomography angiography (CTA), and magnetic resonance angiography (MRA), which help visualize the blood vessels. The goal of treatment is to restore blood flow in the blocked artery and prevent further complications. Both nonsurgical and surgical treatments can be used, depending on the size of the blood clot and the patient’s overall health. Treatments may include anti-clotting medicines and clot-busting drugs, surgery to remove the clot, or a procedure to widen the artery and place a stent (a small tube) to keep it open. The treatment plan will be adapted according to the severity of the condition and the risk of potential complications.

The subclavian artery originates from different areas on the right and left sides of the body, respectively. It supplies blood to the upper limb, neck, and brain, running through the chest from where it begins, going under the collar bone, and over the first rib before it reaches the shoulder area. Along its path, it gives off several branches, each supplying different areas and functions.

The subclavian artery is divided into three parts. The first part stretches from its beginning to the inside border of the front muscle of the neck. The second part lies behind this muscle, and the third part runs from the outside border of this muscle to the outside border of the first rib. Some of its key branches include the vertebral artery, internal mammary artery (IMA), thyrocervical trunk, costocervical trunk, and dorsal scapular artery. Each of these branches supply different areas and perform distinct functions.

The vertebral artery, which originates from the first part of the subclavian artery, travels through the holes of the neck bones to provide blood to the brain and spinal cord. Even when the subclavian artery is narrow or blocked, blood from the other vertebral artery or other contributors inside the brain can flow in the opposite direction through the network of arteries at the base of the brain to help keep the brain supplied with blood. This process can lower the risk of brain cell death and stroke in individuals with a narrow or blocked subclavian artery, serving as an essential backup system to help preserve brain function.

The IMA, also known as the “internal thoracic artery,” runs down the inside of the chest wall, supplying blood to the chest wall and breasts. This artery is often involved in coronary artery bypass grafting (CABG), a type of heart surgery. The thyrocervical trunk divides into the inferior thyroid, transverse cervical, and suprascapular arteries, which provide blood to the thyroid gland, muscles of the neck, and shoulder region, respectively. The costocervical trunk supplies blood to the upper parts between the ribs, deep neck muscles, and upper parts of the spinal cord. The dorsal scapular artery, which can run separately or off the transverse cervical artery, supplies the shoulder girdle and muscles of the back. The subclavian artery changes its name to the axillary artery after it passes the edge of the first rib.

The subclavian artery is responsible for supplying large areas of the head, neck, and upper limb with blood. Understanding this artery’s anatomy is key to diagnosing and managing conditions such as subclavian artery thrombosis and carrying out surgical procedures in the shoulder, arm, and neck areas.

What Causes Subclavian Artery Thrombosis?

Subclavian artery thrombosis, which is a blood clot in the artery just beneath your collarbone, is most commonly caused by atherosclerosis. Atherosclerosis is when your arteries become clogged with fatty substances, causing them to narrow and restrict blood flow. However, there are rarer causes for this condition as well.

These can include inherent physical abnormalities, fibromuscular dysplasia (a condition that causes abnormal growth or placement of cells in your arteries), neurofibromatosis (a genetic disorder causing tumors to form on nerve tissue), autoimmune vasculitis (inflammation of the blood vessels due to an overactive immune response), exposure to radiation, accidental injury during medical procedures, and other mechanical causes like injury or compression disorders.

Risk Factors and Frequency for Subclavian Artery Thrombosis

Subclavian artery thrombosis, a vascular disease affecting the artery located below the collarbone, occurs in about 11% to 18% of patients with peripheral vascular diseases. When someone has this condition, there’s a 50% chance that they may also have coronary artery disease. They also have a 27% likelihood of having lower extremity artery disease, and a 29% chance of simultaneous carotid artery disease.

People with subclavian artery thrombosis face a heightened risk of developing coronary artery disease, transient ischemic attack (a brief stroke-like attack), and cerebrovascular ischemia or infarction (a type of stroke). This is due to the common cause of these conditions. The risk is higher, particularly if the lesion is on the left side.

Subclavian artery thrombosis is often missed in diagnoses. It is more likely to occur in the left subclavian artery, with the incidents on the left side being four times more than those on the right.

Signs and Symptoms of Subclavian Artery Thrombosis

Subclavian artery thrombosis, or a blockage in the artery underneath the collarbone, can result in various symptoms depending on how much blood flow has been rerouted. Symptoms affecting the upper arm can include muscle fatigue or claudication (pain in the muscles while doing activity), pain at rest, and even death of finger tissue due to tiny clots.

When the blockage occurs before the origin of the vertebral artery, it can lead to a condition known as vertebrobasilar insufficiency. This condition happens when strenuous activities lead to a backward flow in the vertebral artery, reducing the blood reaching the basilar artery. This blood insufficiency can induce neurological symptoms such as:

Double vision
Drop attacks (sudden falls without loss of consciousness)
Fainting
Unsteady gait
Vertigo
Speech and swallowing difficulties
Dizziness
Uncontrolled eye movements
Ring in the ears
Hearing loss
Facial numbness

A rare complication of subclavian artery blockage can occur in patients who had a specific heart bypass surgery. In these patients, chest pain can develop due to disrupted blood flow to the grafted artery. A thorough physical examination may reveal unequal blood pressure between the arms, weaker or absent pulses in the upper arm, neck, or above the collarbone sounds (bruits), and signs of reduced blood to the arms such as gangrene skin changes or tiny hemorrhages under the fingernails. Additionally, circulation to the brain should be assessed.

Signs that suggest subclavian artery blockage include uneven blood pressures in the arms, weak or absent pulses, and tissue death (from ulcers or gangrene) in digit of the arm. A difference in blood pressure of more than 10 mm Hg between the arms has a positive predictive value of 13% for diagnosing the blockage. If the difference rises to 15 or 20 mm Hg, the certainty of diagnosis improves to 67-100%.

Subclavian artery blockage’s high-grade form is a serious medical emergency that can jeopardize the affected limb and brain function due to insufficient blood flow. Therefore, prompt identification and treatment are crucial to prevent severe consequences.

Testing for Subclavian Artery Thrombosis

If your doctor suspects that you might have a subclavian artery thrombosis (a blood clot in the artery under your collarbone), one effective, non-invasive imaging test they can use to determine this is a Duplex ultrasound with color flow. Typical signs of the clot that the ultrasound might reveal include abnormal wave shapes, rapid changes in color (indicating turbulent blood flow), and increased speed of blood flow at the site of the narrow section of your artery.

Doppler ultrasonography, another ultrasound technique that studies blood flow, can also show a reversal of blood flow in the vertebral arteries on the same side as the clot. This is often seen in a condition known as subclavian steal syndrome.

A high-speed blood flow detected by ultrasound indicates more than 50% narrowing in the obstructed artery. But, it can be challenging to differentiate between severe subclavian artery stenosis (narrowing of the artery) and complete obstruction. The majority of these narrowings are located in the beginning portion of the artery. Signs indicating extreme narrowing or stenosis include the following: one-phase, post-narrowing flow and altered blood flow in the vertebral artery on the same side.

Detailed ultrasound evaluations are important to detect a significantly narrow or blocked right brachiocephalic trunk (the artery that supplies blood to the right side of the brain and the right arm). If there is sluggish blood flow in both the right subclavian and common carotid arteries, higher-grade narrowing might be present. In such cases, further assessment like a vascular CT or magnetic resonance angiography (MRA) may be needed to clearly visualize the anatomy of the arteries.

A CT angiogram (CTA) can offer detailed information, crucial for ruling out problems related to the vascular system in the area of the chest where your arms connect to the rest of your body, a condition known as vascular thoracic outlet syndrome. This type of imaging can also clearly distinguish lesions in specific arterial areas.

In more critical cases where surgical intervention might be needed, MRA and multi-detector CT (MDCT) angiography are preferred. MRA provides both shape and function characteristics of the artery, enabling precise differentiation and measures the severity of the narrowing. MDCT angiography, on the other hand, offers detailed images of the diseased subclavian artery condition. To get the best possible results from an MDCT examination, there should be careful arm positioning, optimal use of contrast material, thorough data acquisition, and careful setting of reconstruction parameters.

If your doctor will use your internal mammary artery for a type of heart surgery known as coronary artery bypass graft or if you’ve had peripheral artery disease or a noticeable uneven blood pressure (exceeding 10mmHg) in your upper limbs, they might suggest screening for subclavian artery narrowing. The diagnosis is confirmed once the reversal of left vertebral artery blood flow is detected on Doppler ultrasound and severe left subclavian artery is confirmed with imaging.

Treatment Options for Subclavian Artery Thrombosis

Treating a narrowing of the subclavian artery (the artery located beneath the collarbone) in a timely manner is essential to saving the affected limb and preventing serious complications like limb loss or stroke. There are a variety of treatment methods available. These can include medications, minimally invasive procedures, surgeries, or a combination depending on the patient’s specific symptoms and the condition of their blood vessels.

The choice of treatment for subclavian artery blockage depends on a careful review of the patient’s symptoms, imaging tests, risk factors, and the patient’s unique circumstances. The main aim is to achieve the best outcomes and maintain the health of the limb and blood vessels. Indications for treatment might include severe arm pain, pain in the upper limb during exercise, pain at rest, fingers’ embolization, disruption in blood flow due to a stealing syndrome, heart-related pain due to arterial graft, or leg pain in the presence of an artery graft from the armpit to the groin.

Medical treatments can include aspirin or clopidogrel to prevent clotting, HMG-CoA reductase inhibitors for managing cholesterol, and medications for controlling blood pressure. It’s also strongly recommended that patients quit smoking. For patients with diabetes, controlling blood sugars is especially important, with a target HbA1c below 7.

Surgical intervention might be necessary for patients with symptomatic subclavian artery disease, critical limb ischemia (low blood flow), ineffective response to medical therapy, or contraindications to minimally invasive procedures. Surgical interventions include bypass procedures and artery transposition. These procedures have shown a reduced rate of illness and death.

Minimally invasive procedures include methods like angioplasty, where the narrowed artery is expanded with the help of a balloon or a stent. These procedures have shown high success rates in restoring normal blood flow and improving symptoms.

Another type of treatment involves a device called an Angiojet®, which combines clot-dissolving medication with a mechanical device to remove blockages. This has also shown improved outcomes compared to other methods, with higher success rates and a lower risk of limb amputation within a year.

Revascularization–restoring blood flow to the blocked area–is recommended for most patients with symptomatic upper extremity artery disease. This includes patients experiencing symptoms of transient ischemic attack or stroke, those having artery graft with inner mammary artery, and patients dealing with dysfunction in hemodialysis access, among others. Both minimally invasive and surgical procedures can be considered as options, with comparable outcomes between them.

In some severe cases of subclavian artery narrowing, a step-by-step approach is recommended involving the placement of an antiembolic filter into the left brachial artery for protection, inflating a blood pressure cuff, inflating a catheter along the vertebral artery, placing a stent, and then performing control angiography to evaluate the success of the procedure.

When a doctor tries to figure out if a patient has Subclavian Artery Stenosis, which is a narrowing of the artery, they also need to consider several other conditions that could cause similar symptoms. These conditions include:

Birth defects like an unusual Subclavian artery or an extra rib in the neck can mimic the symptoms of this type of artery narrowing.
Fibromuscular dysplasia, a condition that causes abnormal blood vessel structure, can also result in narrowed arteries.
Neurofibromatosis, a genetic disorder that causes tumors on nerve tissue, may lead to unusual blood vessel growth, creating symptoms similar to Subclavian Artery Stenosis.
Autoimmune diseases like Takayasu arteritis can cause artery inflammation and narrowing, seeming like an artery blockage.
Exposure to radiation may cause Subclavian Artery scarring and narrowing, producing symptoms just like a blocked artery.
Physical causes like injuries or pressure problems such as Thoracic Outlet Syndrome can disrupt blood flow through the artery, resembling an artery blockage.

To accurately diagnose Subclavian Artery Stenosis, doctors use a combination of patient assessments and specific diagnostic tests to differentiate it from these other conditions.

What to expect with Subclavian Artery Thrombosis

The outlook for patients with subclavian artery thrombosis (a blood clot in the artery beneath your collarbone) depends on several factors. These include how severe the blockage is, how quickly treatment is received, the presence of other health conditions, how much tissue damage exists, how well the treatment works, and the development of any complications.

Serious complications can occur if the occlusion (or blockage) is long-lasting and complete, and can include life-changing events like limb loss or a stroke. If the blockage is partial, symptoms might be milder or possibly not noticeable at all.

If this condition is quickly recognized and treated (a process called revascularization, which is the restoration of blood flow), the outlook is generally better. However, other existing health conditions might mean that certain treatments aren’t suitable, which could lead to delays in restoring blood flow and tissue healing.

The amount of damage to the tissue also affects the outlook, with severe complications including limb ischemia (a serious condition in which there is insufficient blood flow to the limb), stroke, or death in the worse cases. Quick and successful revascularization substantially improves the outlook. However, if complications like recurrent thrombosis (the recurrence of blood clots) occur, they can negatively impact the long-term outlook.

Possible Complications When Diagnosed with Subclavian Artery Thrombosis

When a clot forms in the subclavian artery, it can lead to several problematic symptoms and complications, like:

Pain and death of tissues in the upper arm (57% of cases)
Pain in the upper limb during exertion
Experiencing pain in the upper extremity even when at rest
Bits of clots releasing and landing in the fingers
Problems in the back of the brain due to stealing blood flow (37% of cases)
Chest pain resulting from the coronary artery stealing blood through an artery graft (21% of cases)
Pain in the leg when an axillofemoral graft is present

Also, certain complications can happen during the procedures to treat this issue. These include:

Strokes
Tearing of the subclavian artery
Transient ischemic attack (or a “mini-stroke”)
Bits of clots getting released and settling elsewhere in the body
Blood clotting
Bruises caused by blood collecting under the skin
Bleeding
Infections or bleeding at the site where doctors accessed your body

To avoid shifting plaque in the vertebral artery and blocks in the brain and limbs, different protection methods can be used. These include using a filter and a jailed balloon during the procedure. Non-invasive methods, such as inducing increased blood flow by inflating and releasing a blood pressure cuff, can also help.

Preventing Subclavian Artery Thrombosis

To prevent a blood clot in the subclavian artery (a major blood vessel in the upper body), there are several preventive measures that can reduce the risk of complications. These measures include lifestyle changes such as quitting smoking, exercising regularly, and eating a healthy diet. These healthy habits can prevent atherosclerosis (a condition where the arteries harden due to fat accumulation) and the development of diseases related to blood vessels.

Proper management of blood pressure, cholesterol levels, and diabetes can also prevent damage to the arteries and reduce the risk of developing blood clots. Regular health check-ups can help detect any abnormalities in the blood vessels early on, and identify if you’re at risk of developing a blood clot.

If you work in a physically demanding job, using proper ergonomics and protective equipment can help reduce injury to your blood vessels. Being aware of the signs and symptoms of a blood clot in the subclavian artery can help in its early detection and timely treatment, which can lead to better health outcomes and a lower chance of developing further blood clots.

Frequently asked questions

The prognosis for Subclavian Artery Thrombosis depends on several factors, including the severity of the blockage, the speed of treatment, the presence of other health conditions, the extent of tissue damage, the effectiveness of treatment, and the development of complications. Serious complications can occur if the blockage is long-lasting and complete, such as limb loss or stroke. If the condition is quickly recognized and treated, the outlook is generally better, but existing health conditions and delays in treatment can affect the outcome. Successful revascularization improves the prognosis, but complications like recurrent thrombosis can have a negative impact.

Subclavian artery thrombosis is most commonly caused by atherosclerosis, which is when your arteries become clogged with fatty substances. However, there are also rarer causes such as physical abnormalities, fibromuscular dysplasia, neurofibromatosis, autoimmune vasculitis, exposure to radiation, accidental injury during medical procedures, and other mechanical causes like injury or compression disorders.

Signs and symptoms of Subclavian Artery Thrombosis include: - Muscle fatigue or claudication (pain in the muscles while doing activity) in the upper arm - Pain at rest in the upper arm - Death of finger tissue due to tiny clots - Double vision - Drop attacks (sudden falls without loss of consciousness) - Fainting - Unsteady gait - Vertigo - Speech and swallowing difficulties - Dizziness - Uncontrolled eye movements - Ringing in the ears - Hearing loss - Facial numbness - Unequal blood pressure between the arms - Weaker or absent pulses in the upper arm, neck, or above the collarbone - Bruits (abnormal sounds) above the collarbone - Gangrene skin changes or tiny hemorrhages under the fingernails - Difference in blood pressure of more than 10 mm Hg between the arms - High-grade form can jeopardize the affected limb and brain function due to insufficient blood flow

The types of tests that are needed for Subclavian Artery Thrombosis include: 1. Duplex ultrasound: This noninvasive test can detect subtle changes in the waveform or turbulent blood flow, as well as faster blood flow at a narrow spot in the artery. It can also identify if blood is flowing in the opposite direction in the vertebral artery, indicating subclavian steal syndrome. 2. Computerized tomography angiography (CTA): This imaging study provides a detailed look at the arteries and can help rule out vascular thoracic outlet syndrome. It can also distinguish build-up lesions located above the aortic valve in the heart. 3. Magnetic resonance angiography (MRA): This test offers a closer look at the structure and function of the arteries, assisting in the identification and measurement of blockages. It can provide more accurate diagnosis, especially in critical cases where intervention is necessary. 4. Angiography: This type of x-ray imaging is used to see the blood vessels and can confirm severe left subclavian artery narrowing. It is important to note that the choice of tests depends on the patient's specific symptoms, imaging results, and risk factors.

The other conditions that a doctor needs to rule out when diagnosing Subclavian Artery Thrombosis are: - Birth defects like an unusual Subclavian artery or an extra rib in the neck - Fibromuscular dysplasia, a condition that causes abnormal blood vessel structure - Neurofibromatosis, a genetic disorder that causes tumors on nerve tissue - Autoimmune diseases like Takayasu arteritis, which can cause artery inflammation and narrowing - Exposure to radiation, which may cause Subclavian Artery scarring and narrowing - Physical causes like injuries or pressure problems such as Thoracic Outlet Syndrome, which can disrupt blood flow through the artery.

The side effects when treating Subclavian Artery Thrombosis can include: - Strokes - Tearing of the subclavian artery - Transient ischemic attack (or a "mini-stroke") - Bits of clots getting released and settling elsewhere in the body - Blood clotting - Bruises caused by blood collecting under the skin - Bleeding - Infections or bleeding at the site where doctors accessed your body

A vascular specialist or a cardiologist.

Subclavian artery thrombosis occurs in about 11% to 18% of patients with peripheral vascular diseases.

Subclavian Artery Thrombosis can be treated through a variety of methods depending on the patient's specific symptoms and the condition of their blood vessels. Treatment options can include medications, minimally invasive procedures, surgeries, or a combination of these approaches. Medical treatments may involve the use of aspirin or clopidogrel to prevent clotting, HMG-CoA reductase inhibitors for managing cholesterol, and medications for controlling blood pressure. Surgical interventions such as bypass procedures and artery transposition may be necessary for patients with symptomatic subclavian artery disease or critical limb ischemia. Minimally invasive procedures like angioplasty or the use of devices like Angiojet® can also be effective in restoring normal blood flow and improving symptoms. In severe cases, a step-by-step approach involving the placement of an antiembolic filter, inflating a blood pressure cuff, inflating a catheter, placing a stent, and performing control angiography may be recommended.

Subclavian artery thrombosis is a condition where a blood clot forms in the subclavian artery, a large blood vessel in the shoulder area. This clot can significantly reduce blood flow to the area supplied by the vessel, potentially affecting the upper limb, brain, and heart. It can be a medical emergency if the blood vessel is completely blocked, leading to the loss of a limb or stroke if not promptly treated.