What is Subclavian Artery Stenosis?
Peripheral arterial disease (PAD) affects different arteries in the body, causing distinct symptoms. When it involves the subclavian and innominate arteries, it could lead to various conditions like hand discomfort due to poor blood supply, reduced blood flow to the brain, moving blood clots leading to extremity pain, or tissue death seen in the fingertips. Some patients with PAD might experience a condition called ‘coronary steal’ where the blood destined for the heart is diverted elsewhere due to a blockage. They may also experience leg discomfort if they have undergone bypass surgery to improve blood flow in the heart or legs.
When a doctor examines a person with this kind of PAD, they may notice weak pulses in the arm that’s on the same side of the body as the affected artery. There can also be a difference of more than 10mmHg in blood pressure compared to the other arm. The affected hand may feel cooler than the other and in severe cases, there may be signs of tissue death in the fingertips. PAD is more common in people in their 60s or 70s with a history of risk factors like smoking, diabetes, high cholesterol, high blood pressure, PAD affecting the legs, or certain rare inherited or inflammatory conditions like Takayasu arteritis.
What Causes Subclavian Artery Stenosis?
Subclavian artery stenosis is a condition that narrows the subclavian artery, a major blood vessel. This can cause serious health problems because it can reduce blood flow to the arms, brain, and heart. The narrowing often results from atherosclerosis, a condition where arteries harden due to fatty deposits on their inner walls.
Other causes of subclavian artery stenosis can include arteritis (inflammation of the arteries), exposure to radiation, compression syndromes (where blood vessels are squeezed), fibromuscular dysplasia (a disease that changes the structure of the artery’s wall), Takayasu arteritis (a rare type of arteritis that involves the large blood vessels), and neurofibromatosis (a genetic disorder causing tumors to form on nerve tissue).
Additionally, some abnormal conditions that are present from birth, such as an aberrant subclavian artery (when the artery develops in an abnormal place) and right-sided aortic arch (when the main blood vessel from the heart is on the right side instead of the left), may also contribute to the development of subclavian artery stenosis.
Risk Factors and Frequency for Subclavian Artery Stenosis
Peripheral arterial disease (PAD) is a condition that involves the narrowing of major vessels due to a condition called atherosclerosis. Approximately 2% of the population have PAD affecting the subclavian artery. Among adults older than 70 years, around 15% have PAD. Among these, nearly a quarter will need some form of revascularization, and 5% will progress to critical limb ischemia, a severe stage of the disease. The narrowing of the subclavian artery, known as subclavian artery stenosis, is reported in around 1.9% of the general population and 7.1% of those with vascular disease. Most patients do not show symptoms because the disease progresses slowly. Symptoms usually appear once the narrowing of the vessel becomes 50% severe.
Among patients with known PAD, approximately 42% also have disease in a vessel called the brachiocephalic artery. Some patients with PAD also have stenosis, or narrowing, of the left subclavian artery (30% of cases). Among those with subclavian artery disease, half also have coronary artery disease, and a third have carotid or vertebral disease.
In rare instances, there have been cases reported of stenosis in both subclavian arteries.
Signs and Symptoms of Subclavian Artery Stenosis
The left subclavian artery, an important blood vessel in your body, is more likely to experience issues than the right subclavian or innominate arteries. If there is a narrowing (stenosis) only in the left subclavian artery, symptoms are less likely to appear compared to other vessels. However, if the disease also involves other vessels branching from the aorta, like the carotid or vertebral arteries, there might be an increased chance for symptoms like reduced blood flow (steal) or lack of adequate blood supply (ischemia).
Signs and symptoms may include arm fatigue, pain in the muscles or at rest, and even tissue death in the fingers. Some patients may experience symptoms related to decreased blood flow to the brain and spinal cord, such as visual problems, fainting, loss of coordination, dizziness, difficulty understanding language, speech problems, and facial numbness.
In those who had previous heart bypass surgery with grafting of the internal mammary artery, symptoms of heart disease like chest pain (angina) due to reduced blood flow to the heart might be common.
A thorough physical exam is crucial for diagnosis, even though images (like scans) often confirm it. During the examination, healthcare professionals may observe the following:
- Different blood pressures in each arm
- Constant low blood pressure in rare cases where both subclavian arteries are narrowed
- Faint or significantly weakened pulse in the upper limbs and a blood pressure difference of more than 15 mmHg between the two arms
- Nervous system and heart problems
- The sound of turbulent blood flow (bruits) in the arteries
- Skin ulcers and gangrene (dead tissue)
- Small, dark, purplish spots under the nails (splinter hemorrhages)
- An Ankle-Brachial Index (ABI) value of more than 1.3 in patients with both subclanian arteries affected
- Signs of decreased blood flow to the brain and spinal cord such as fainting, lack of coordination and difficulty swallowing.
Testing for Subclavian Artery Stenosis
If your doctor suspects you have an issue with the subclavian artery (a major blood vessel found beneath your collarbone), they’ll start with some basic checks. They’ll measure the blood pressure in both of your arms as a difference could indicate a problem. They might also listen for abnormal noises, called bruits, in the blood vessels in your neck. Less common signs your doctor would look for include sores or gangrene on your fingers, or unusual red or purple lines under your nails, which can occur due to small blood clots.
The easiest and least harmful way for doctors to better examine your arteries is through an imaging technique called duplex ultrasound that uses color to show how blood is flowing. Specific things your doctor will monitor for include abnormal waveforms, rapid blood flow around narrowed arteries, or blood flowing in the wrong direction in your vertebral artery, which is a sign of a specific condition known as subclavian steal syndrome.
A CT scan can also provide a high-quality image of your artery and help identify the exact location and length of any problematic areas. However, a CT scan is less effective at showing how hard (calcified) your arteries may have become.
For a more accurate picture, magnetic resonance (MR) angiography can be used but sometimes the results can be misleading, making the disease seem more severe than it really is. More invasive (meaning a small tube has to be inserted into your body) angiography can provide a more detailed map of your artery and better characterize any narrowing. However, such a procedure comes with a small risk of stroke.
Treatment Options for Subclavian Artery Stenosis
Most people with a narrowing of the subclavian artery, the one responsible for circulating blood to your arms and head, due to fatty deposits, known as atherosclerosis, don’t show symptoms. If there are symptoms, then treatment may be needed.
An endovascular approach, a method involving the use of a small tube passed through your blood vessels to the problem area, is often the first line of treatment. This method, which includes procedures like angioplasty and stenting, is less invasive, meaning it doesn’t require large incisions or much recovery time compared to open surgery. This treatment can provide relief for more than ten years and is typically attempted before considering open surgery. However, for low-risk patients, an open surgical approach may prove to be more effective.
There are different techniques for managing subclavian artery stenosis through surgery too. These include moving the subclavian artery to the carotid artery (a major blood vessel in the neck), or bypassing the blockage in the subclavian artery by creating a new path for blood to flow using a graft from another area of the body. If the endovascular approach is unsuccessful, or if the previously placed stents become blocked, surgical intervention is recommended.
Signs that treatment might be required include severe arm pain, pain in the upper limbs even at rest, blocked blood vessels in the fingers, issues with blood flow to the brain due to blood being “stolen” from the brain and redirected to the arm, chest pain due to blood being “stolen” from the heart and redirected to the chest, and leg pain due to blocked blood flow in an implanted graft.
Patients are given medications like aspirin or clopidogrel, both of which thin the blood, or HMG-CoA reductase inhibitors, which lower cholesterol levels, or medicines like ACE inhibitors or angiotensin receptor blockers that lower blood pressure. Additionally, patients are advised against smoking and, if they are diabetic, are asked to keep their blood sugar levels under control.
For serious cases of subclavian artery stenosis, an array of surgical treatments such as axillary–axillary bypass, carotid-subclavian bypass, or moving the subclavian artery could be necessary.
Other recognized procedures include pharmacomechanical thrombectomy (PMT), a procedure where a device removes the blockage and medication is used to dissolve the clot. In some cases, PMT is used alongside catheter-directed therapy, where medication is directly delivered to the clot through a small plastic tube. Interestingly, patients who only underwent the PMT procedure had better outcomes than those who had both treatments.
All patients with symptomatic upper limb artery disease are recommended to control risk factors and look into the best possible treatment to reduce cardiovascular risk. However, there are certain groups of symptomatic patients where revascularization, the process of restoring blood flow to an organ or tissue, might be necessary.
For planning revascularization, both endovascular and surgical procedures are recommended. The results for endovascular and open repair and the risk of serious complications were found to be similar.
In a case report, a step-by-step set of actions were recommended to treat severe clot-induced narrowing of the left subclavian artery. These included the placement of a long guiding sheath, the placement of an anti-embolic filter into the left brachial artery, blood pressure cuff inflation over the left brachial artery, and a coronary balloon catheter being inflated at the first segment of the vertebral artery, among other steps.
Also, three measures were recognized that could help prevent potential complications: plaque shift to the vertebral artery, brain complications, and distal limb blockage.
What else can Subclavian Artery Stenosis be?
There are several health conditions related to the blood vessels in the neck and brain areas that one could have, including:
- Carotid artery disease
- Subclavian steal syndrome
- Stroke
- Cardiogenic shock in people with narrowing of both shoulder arteries (bilateral subclavian artery stenosis)
What to expect with Subclavian Artery Stenosis
Carotid-subclavian artery bypass is a procedure that uses a man-made graft, and it’s generally regarded as safe. The chances of death from this procedure range from 0 to 3%, and the risk of having a stroke from it can be from 0 to 5%.
Recent research shows that endovascular procedures, less invasive treatments performed inside the blood vessels, are effective. In fact, studies show over 95% of people undergoing these treatments had their symptoms significantly improved or eliminated.
Possible Complications When Diagnosed with Subclavian Artery Stenosis
Breaking or damaging of the stent after a non-surgical, minimally invasive procedure is recognized as a possible consequence of the process. It’s not uncommon to observe that the subclavian artery, an artery located under your collar bone, can get blocked again after a stent fracture.
If a person has a disease in the starting part of their left subclavian artery, they are likely to experience recurrent heart issues due to a condition called the ‘coronary-subclavian steal syndrome’.
Common Complications:
- Stent damage or fracture post-procedure
- Re-blockage of the subclavian artery due to stent fracture
- Recurrent heart problems in patients with a disease in the starting part of the left subclavian artery
Preventing Subclavian Artery Stenosis
In addition to knowing what to expect from surgery, it’s important for patients to understand the root cause of their condition. A common cause of a narrowing of the subclavian artery (an artery in your chest), known as Subclavian artery stenosis, is a condition called atherosclerosis. This usually affects the left subclavian artery. Atherosclerosis is when your arteries harden and narrow due to a buildup of substances like cholesterol and fat.
Prevention is key. The same steps that can be taken to prevent this condition can also help to stop it from getting worse or coming back after surgery. Most significantly, this involves preventing atherosclerosis, Peripheral Artery Disease (a condition where unstable fatty deposits fasten themselves to the walls of your arteries), and Subclavian artery stenosis. This can be done by making some healthy lifestyle changes including eating a well-balanced diet, exercising regularly, maintaining a healthy weight, and avoiding all forms of smoking and tobacco.
It’s also crucial to effectively manage other health conditions you may have. This is because you can decrease your risk of vascular problems by keeping conditions like high blood pressure, high cholesterol levels, and elevated blood sugar levels under control. Taking prescribed medication for these conditions can also aid in this.
