Renal Artery Stenosis – Causes, Symptoms, and Treatment

Renal artery stenosis is the condition in which the arteries that actually carries blood to the kidneys starts to narrow. Treatment for renal artery stenosis includes changes in lifestyle, certain medication and surgery. It is a serious condition and can also leads to chronic kidney diseases or kidney failure.

What is Renal Artery Stenosis?

Renal artery stenosis (RAS) is a disorder in which the arteries that carry blood from the heart to the kidneys become narrow. In the human body, there are two renal arteries that supply oxygen-rich blood to the left and right kidneys.

Any of these renal arteries can develop stenosis. When the renal arteries get narrow, it reduces blood flow to the kidney tissues, which can be mistaken by the body as low blood pressure and can increase the blood flow in the overall body.

This can increase the chances of getting hypertension (High blood pressure), serious kidney disease and even kidney failure. However, it is mostly seen in older people with atherosclerosis and can worsen over time.

Who can get Renal Artery Stenosis (RAS)?

People who have atherosclerosis are mainly at high risk of getting renal artery stenosis easily. Atherosclerosis is a build-up of sticky substances like cholesterol and fat in one of the artery walls, and this sticky build-up is known as plaque.

Even risk factors for renal artery stenosis include:

• Family history of cardiovascular disease
• Obesity
• Diabetes
• High cholesterol
• Poor diet (includes high amounts of fat, sodium and sugar)
• Smoking

What are the symptoms of renal artery stenosis?

Renal artery stenosis (RAS) does not show any specific symptoms. However, the condition can show signs like high blood pressure that is hard to control and reduced kidney functions only after the disease is in its advanced stage.

The condition may not be discovered individually but can be suspected while testing for some other disease. The healthcare provider can also recommend you to test for Renal Artery Stenosis if they suspect problems like:

• High blood pressure that is hard to control and gets worse without any explanation.
• Problem of high blood pressure at an early age, like 30.

Symptoms that show renal artery processing:

• High blood pressure, hard to manage
• Elevated protein levels in urine
• Signs that show problems with kidney functions
• A whooshing sound of blood flow in your narrowed vessel is detected by the doctor through a stethoscope.
• Overload fluid and swelling in body tissues.

Some of the symptoms of poor kidney function may include:

• Difficulty in sleeping
• Fatigue
• Concentration problems or confusion
• Loss of appetite
• Headaches
• Muscle cramps
• Edema (Swelling due to fluid build-up)
• Shortness of breath
• Unexplained weight loss
• Nausea and vomiting
• Urinating less or more often

What causes renal artery stenosis?

Most of the time, the reason for renal artery stenosis is atherosclerosis. However, the other reason can be kidney dis-function. Let us discus the two main causes for renal artery stenosis(RAS).

Build-up on renal (Kidney) arteries: It is a process in which plaque, which is made up of cholesterol, fats and other materials, starts to collect on the walls of the blood vessels, even on those leading towards the kidneys.

This build-up is also known as atherosclerosis, and this is most common in old people and is the main reason for renal artery stenosis. However, these deposits on the walls get larger and get harder over time. It reduces the blood flow, causes kidney scarring and starts to narrow the arteries.

Fibromuscular dysplasia: It is rare when renal artery stenosis happens due to the condition call fibromuscular dysplasia. This is happens when the cells in the kidney arteries goes under some abnormal growth or does not grow as it should.

It mostly starts in childhood and commonly seen in women or younger people. In image test the narrow sections alternating with wider sections and can give a bead-like appearance result of the artery.

However, narrow kidney arteries and fibromuscular dysplasia can affect other arteries too in your body and may cause complications.

It is rare that renal artery stenosis can be a result of other conditions, such as growth that develops in your abdomen or the inflammation of the blood vessels that can even press your kidney arteries. It can happen in one or both the arteries.

Diagnosis and test

How renal artery stenosis is diagnosed?

Diagnosing renal artery stenosis may include:

• A physical exam is done by your healthcare provider to check through a stethoscope over your kidney area to listen for sounds that may indicate the artery to your kidney is narrow.

• Blood and urine tests to check your kidney function and measure the level of hormones that regulate blood pressure.

• May ask you for details about your medical history.

Test to check renal artery stenosis

Renal artery stenosis can be done by image tests, which include:

CT scan: In a CT scan, a computer is connected to an X-ray machine that creates a detailed image of the cross-section of the renal arteries. You may even get a dye injection to show the blood flow.

Doppler ultrasound: A high-frequency sound wave machine helps you healthcare provider to check the arteries and the kidneys function. This process also helps your healthcare provider to find and blockage in the blood vessel and measure their severity.

Magnetic resonance angiography (MRA): MRA is used to produce 3D images, it uses strong magnetic fields and radio waves to results of the kidney and renal arteries. They may use a dye injection to showcase blood vessels during imaging.

Renal arteriography: This is a special type of X-ray that helps your healthcare provider to find the blockage in the renal arteries, and sometimes, it also opens up the narrowed part with a stent or balloon.

The healthcare provider will use a dye injection before going for an X-ray; they will use a thin tube (Catheter) to inject the dye, which will help outline the arteries and show blood flow more clearly. This test is only recommended by your doctor if you need a small tube to be inserted in your blood vessel to widen it.

How can renal artery stenosis be treated?

Treatment for renal artery stenosis is easy and more likely to involve lifestyle changes, medication and a procedure that can help restore the normal blood flow to the kidneys.

Sometimes surgery can be an option, but only for people who are suffering from severe renal artery stenosis, have high blood pressure that can be managed by medication or have a risk of arterial blockage. However, the combination treatment is the best option. It depends on your overall health and symptoms and what kind of special treatment your doctor will suggest.

Lifestyle changes

To manage renal artery stenosis (RAS), your healthcare provider will suggest some healthy lifestyle changes to help lower blood pressure. Some of them include:

• Getting regular exercise
• Quit smoking
• Losing some extra weight
• Eating a healthy diet that is low in sodium, cholesterol, fats and sugar

Certain medications

To manage high blood pressure due to renal artery stenosis or some other condition, your healthcare provider will suggest certain medications; making healthy lifestyle changes and getting proper medication will help in RAS and slow down or prevent the growing kidney disease.

Some of the combinations of medication your healthcare provider will suggest for renal artery stenosis are:

• Angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) help your blood vessels relax and block certain hormones that may cause narrow blood vessels.
• Aspirin: It thins your blood, which helps blood flow easily through the arteries.
• Diuretics: These are also called water tablets, which help your body eliminate excess water and sodium from the kidneys.
• Calcium channel blocker and beta-blockers that helps relax blood vessels and reduce high blood pressure.

Your doctor will suggest suitable medication for your condition after a proper diagnosis.

Surgery

Your healthcare provider may suggest surgery for renal artery stenosis only if it is serious and can’t be treated with lifestyle changes and medication. The main surgeries that are done for RAS include:

• Renal artery bypass: A surgery that helps to reroute the blood flow to your kidney by bypassing the blocked or narrowed renal artery. The surgeon will use a blood vessel graft (mainly from the person’s leg) or an artificial tube if required.  The tube or graft will be sewn in between the blockage and the kidney.

• Angioplasty and stenting: In this surgery a thin, flexible tube is inserted into the narrowed renal artery. Then they will inflated a tiny balloon into your artery to widen it and then place a small mesh tube to your artery to keep it open for better blood flow in your kidney. It is a most common type of surgery for RAS and a minimally invasive procedure.

• Renal endarterectomy: A type of surgery done to remove the substances and plaque that are narrowing the artery and blocking the blood flow.

How can a person prevent renal artery stenosis?

A person can reduce the risk of renal artery stenosis by:

• Doing exercise regularly.
• Eating a healthy diet.
• Managing a healthy body weight and blood pressure.
• Quitting smoking.

Conclusion

Renal artery stenosis is a serious condition but can be treated with simple lifestyle changes and medication. In some severe condition it need surgery.

As the condition grows without knowing it can cause hard blockage and can be dangerous. If anybody finds these symptoms should immediately consult to the doctor and start the treatment.

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