How to Diagnose Renal Artery Stenosis?
Renal artery stenosis (RAS) is a narrowing of the arteries that supply blood to the kidneys. When these arteries become restricted, blood flow to the kidneys decreases, impairing their ability to filter waste and regulate blood pressure. If left untreated, renal artery stenosis can lead to high blood pressure (hypertension), kidney failure, and an increased risk of heart disease.
To diagnose RAS, healthcare providers use a combination of methods. It often starts with a physical examination and could include blood tests, urine tests, imaging tests, and blood pressure monitoring.
At CACVI, we have over 30 years of experience in handling vascular conditions such as varicose veins, diabetic foot ulcers, renal artery stenosis, etc. Our specialists strive to create personalised treatment plans to help you regain good vascular health. Schedule an appointment with us today for more information on renal artery stenosis.
In this blog, you will learn about renal artery stenosis and its diagnostic methods. We will also cover treatment options for renal artery stenosis.
What Is Renal Artery Stenosis?
Renal artery stenosis (RAS) is a condition that occurs where one or both of the renal arteries become narrowed or blocked, restricting blood flow to the kidneys. This is a serious issue because the kidneys typically require an adequate amount of blood to filter waste and regulate blood pressure.
When blood flow is reduced due to atherosclerosis or fibromuscular dysplasia, it can lead to renovascular hypertension (high blood pressure caused by poor kidney function) and potentially progress to kidney failure. Without treatment, renal artery stenosis can lead to ischemic nephropathy, chronic kidney disease, and other severe complications.
Atherosclerosis is the most common cause of renal artery stenosis. This condition occurs when plaque (a buildup of fat, cholesterol, and other substances) accumulates on the artery walls, causing them to narrow. Over time, the reduced blood flow can damage kidney tissue, resulting in impaired renal function and increased blood pressure.
On the other hand, Fibromuscular dysplasia is a less common cause of RAS, especially in younger individuals. This condition affects the structure of the renal arteries, causing segments of the artery walls to thicken, narrow, or form a “string of beads” appearance. Unlike atherosclerosis, fibromuscular dysplasia is not related to plaque buildup but can still significantly reduce blood flow to the kidneys.
Risk Factors – Who Gets Renal Artery Stenosis?
Certain factors increase the risk of developing renal artery stenosis. These include:
- Age and Gender: Renal artery stenosis is more common in people over the age of 50, particularly in men.
- Hypertension (High Blood Pressure): Chronic high blood pressure can damage blood vessels. This makes them more susceptible to narrowing.
- High Cholesterol: Elevated cholesterol levels contribute to the formation of plaque in the arteries. This then leads to atherosclerotic renal artery stenosis.
- Diabetes: Diabetes increases the risk of atherosclerosis, which can affect the renal arteries.
- Atherosclerosis: People with a history of coronary artery disease or peripheral artery disease are at greater risk of developing RAS.
- Smoking: Smoking accelerates the damage to blood vessels. This increases the risk of artery stenosis.
- Family History: A family history of cardiovascular disease, hypertension, or renal conditions raises the likelihood of renal artery stenosis.
- Obesity: Excess weight contributes to high blood pressure and high cholesterol, which increase the risk of RAS.
- Other Medical Conditions: Autoimmune diseases such as systemic lupus erythematosus and chronic kidney disease (CKD) can also lead to or worsen RAS.
Patients at high risk for RAS, such as those with uncontrolled high blood pressure, diabetes, or atherosclerosis, should be screened regularly. For high-risk individuals, it is recommended to undergo screening annually or as advised by a healthcare provider, especially if they have persistent high blood pressure that does not respond to treatment.
Symptoms of Renal Artery Stenosis
Renal artery stenosis is a condition characterized by the narrowing of one or both renal arteries, reducing blood flow to the kidneys. This can lead to various symptoms, including high blood pressure, which is often difficult to control. This condition is also known as renovascular hypertension.
Another symptom is kidney dysfunction. If you have renal artery stenosis, you may notice signs of kidney failure, such as elevated creatinine levels. This usually occurs due to reduced blood flow. Similarly, you may notice unexplained fluid retention, resulting in swelling (edema) in the legs, ankles, or feet. You could also notice flank pain in the side, which may indicate impaired kidney function.
Furthermore, pulmonary edema is a symptom of renal artery stenosis. This refers to sudden fluid buildup in the lungs, especially during hypertensive crises. Additionally, you can notice changes in urination, such as reduced urine output or other changes in urination patterns.
You should seek medical attention if you experience any of the following warning signs, as they may indicate renal artery stenosis or worsening kidney function.
How to Diagnose Renal Artery Stenosis?
Diagnosing renal artery stenosis (RAS) at the early stage is important to prevent serious complications such as high blood pressure, kidney dysfunction, and even kidney failure. At CACVI, we are dedicated to providing the best diagnostic services for detecting renal artery stenosis. Our expert team uses the latest technology and diagnostic tools to ensure that you receive the most accurate diagnosis and personalized treatment plan possible. Contact us now!
Here’s a breakdown of how to diagnose renal artery stenosis:
Medical History and Physical Exam
The diagnostic process for renal artery stenosis begins with a thorough medical history and physical examination. Physicians will review your personal and family medical history. They will especially pay attention to blood pressure levels, any previous cardiovascular issues, and symptoms such as unexplained fluid retention or decreased kidney function.
Understanding the patient’s risk factors, such as a history of peripheral artery disease, atherosclerotic disease, or renovascular hypertension, helps guide further diagnostic testing.
Blood Tests
A series of blood tests are often the first step in evaluating kidney health. Typically, blood tests give physicians an initial overview of potential kidney damage or arterial atherosclerotic emboli.
These blood tests may include kidney function tests to assess how well the kidneys are filtering blood. For this, tests like serum creatinine and glomerular filtration rate (GFR) are used.
You may also undertake tests to check your cholesterol levels. This is because high cholesterol levels increase the risk of atherosclerotic renal artery stenosis, which can contribute to the narrowing of the renal arteries.
Radiology Tests
Several imaging tests provide visual confirmation of renal artery stenosis. For example, doppler ultrasound is a vascular ultrasound non-invasive test that measures blood flow in the renal arteries using sound waves. It helps detect narrowing or blockages in the arteries. Doppler ultrasound is particularly useful in identifying cases of distal renal artery stenosis or segmental renal artery stenosis.
Another helpful radiology test is CT Angiography (CTA). This is considered the gold standard for visualizing renal artery stenosis. CTA uses contrast dye and X-rays to produce detailed images of the blood vessels, making it effective for diagnosing even subtle blockages or narrowing in the main renal artery and its branches.
There is also Magnetic Resonance Angiography (MRA), which uses magnetic fields and radio waves to generate images of the blood vessels. It is highly useful in cases where radiation exposure or contrast agents used in CT scans may be a concern, especially for patients with reduced kidney function.
Invasive Tests
In some cases, non-invasive tests may not provide enough detail, and invasive diagnostic procedures are required to confirm the diagnosis of renal artery stenosis. One such test is renal arteriography, known as the most precise method for diagnosing renal artery stenosis. During the procedure, a catheter is inserted into the artery, and contrast dye is injected to provide highly detailed X-ray images of the arteries.
While renal arteriography is highly effective in diagnosing renal artery occlusion or fibromuscular dysplasia, it is invasive and carries some risks. These include contrast-associated nephropathy, arterial injury, or atherosclerotic emboli. These risks are weighed against the benefits, particularly in cases where non-invasive methods are inconclusive or when planning surgical intervention.
What Are the Long-term Effects of Untreated Renal Artery Stenosis?
Renal artery stenosis (RAS) occurs when the renal arteries that supply blood to the kidneys become narrowed due to conditions like atherosclerosis or fibromuscular dysplasia. Untreated RAS leads to reduced blood flow to the kidneys, which impairs their ability to filter waste and regulate fluids. Over time, this can cause chronic kidney disease (CKD), characterized by a gradual loss of kidney function. As CKD progresses, patients may experience symptoms such as fatigue, swelling (edema), and difficulty concentrating. If RAS is not addressed, CKD can evolve into a life-threatening condition known as end-stage renal disease (ESRD), where the kidneys fail completely, requiring dialysis or a kidney transplant.
Similarly, untreated renal artery stenosis can lead to hypertension. The kidneys play a vital role in regulating blood pressure, and when they detect low blood flow, they release hormones that cause the body to retain salt and water, raising blood pressure. Persistent high blood pressure strains the heart, arteries, and kidneys, increasing the risk of a heart attack and stroke. In extreme cases, untreated hypertension linked to RAS can result in flash pulmonary edema. This is a sudden and severe buildup of fluid in the lungs, which is a medical emergency.
Like RAS, peripheral artery disease (PAD) results from atherosclerosis, where plaque builds up in arteries outside the heart. While PAD primarily affects the legs, the systemic nature of atherosclerosis means that patients with RAS are also at higher risk of developing PAD. Both conditions reduce blood flow, but PAD affects the extremities, while RAS impacts kidney function.
In addition, renal artery stenosis contributes to an increased risk of heart disease. The narrowing of the renal arteries mirrors atherosclerosis in other arteries, such as those leading to the heart. Patients with untreated RAS often develop coronary artery disease, which can lead to heart attacks or heart failure.
Furthermore, ischemic nephropathy occurs when the kidneys suffer damage due to reduced blood flow. In the context of RAS, this condition develops slowly as the kidneys become starved of oxygen and nutrients. Over time, ischemic nephropathy can cause permanent kidney damage, contributing to the development of Chronic Kidney Disease and, ultimately, End-Stage Renal Disease.
Renal Artery Stenosis vs Peripheral Artery Disease: What is the Difference?
Although both RAS and PAD involve the narrowing of arteries due to atherosclerosis. However, their primary effects differ. Renal artery stenosis reduces blood flow to the kidneys, impairing their function and contributing to hypertension and kidney disease.
On the other hand, peripheral artery disease affects the blood vessels in the legs and arms, leading to pain, cramping, and, in severe cases, tissue damage or amputation. While both conditions stem from similar vascular issues, RAS has a direct impact on kidney health, while PAD primarily affects circulation to the extremities.
Treatment Options for Renal Artery Stenosis
Effective management of renal artery stenosis involves a combination of medications, minimally invasive procedures, and surgical interventions. By addressing the root cause of RAS, treatment can significantly extend life expectancy and improve overall health.
Medications
Medications are often the first line of treatment in managing renal artery stenosis, especially in controlling high blood pressure and preventing further complications. Medications may also be used alongside procedures to manage symptoms and protect the kidneys.
Typically, antihypertensive agents like angiotensin-converting enzyme (ACE) inhibitors and angiotensin II receptor blockers (ARBs) help lower blood pressure. They do this by blocking the production of angiotensin II, a hormone that narrows blood vessels and increases blood pressure.
Statins are also medications you can use for renal artery stenosis as they lower cholesterol levels and slow the progression of arterial plaque buildup in the renal arteries. You can also use antiplatelet drugs like aspirin to reduce the risk of blood clots in the narrowed arteries. This can improve blood flow and protect against heart disease.
Minimally Invasive Procedures
In cases where medications alone are insufficient to manage RAS, minimally invasive procedures may be necessary to restore blood flow and protect kidney function. This includes procedures like angioplasty and renal artery stenting.
Angioplasty is a procedure that involves inserting a small balloon into the narrowed section of the renal artery and inflating it to widen the artery and improve blood flow. Angioplasty is often the first step in treating renal artery stenosis when medications fail to control symptoms.
In conjunction with angioplasty, a small mesh tube (stent) is often placed in the artery to keep it open and ensure long-term blood flow improvement. Renal artery stenting helps restore normal kidney function and reduce hypertension.
Surgical Treatments
For severe cases of renal artery stenting where less invasive treatments are not effective, surgical intervention may be required. It could be a renal artery bypass surgery that involves rerouting blood flow around the blocked or narrowed section of the renal artery using a vein or synthetic tube. Bypass surgery is generally reserved for complex cases where angioplasty and stenting are not feasible.
Similarly, it could be a renal artery endarterectomy, a surgery that involves removing plaque buildup from the inside of the renal artery to improve blood flow. While effective, it is a more invasive procedure and is usually considered when less invasive options are unsuitable.
Ongoing Monitoring and Follow-Ups
After treatment, ongoing monitoring is important to ensure the success of the procedure and to prevent the recurrence of renal artery narrowing. It is important to undergo regular tests to measure glomerular filtration rate (GFR) and serum creatinine levels which help assess kidney function and detect any potential damage caused by RAS.
Since hypertension is a key complication of RAS, frequent monitoring of blood pressure is also essential to ensure it remains under control after treatment.
Healthy Lifestyle Changes for Renal Artery Health
Hypertension is both a cause and consequence of renal artery stenosis. By managing your blood pressure, you can prevent further damage to the renal arteries. Regular monitoring, along with medications prescribed by your healthcare provider, can help you maintain healthy blood pressure levels. Lifestyle measures such as reducing salt intake, maintaining a balanced diet, and staying physically active are also key to managing high blood pressure.
It also helps to quit smoking as smoking contributes to atherosclerosis. This is the buildup of plaque in the arteries, which worsens renal artery stenosis and increases the risk of other cardiovascular diseases. By quitting, you not only improve blood flow but also lower your risk of further arterial narrowing and renal artery occlusion.
Furthermore, you should keep cholesterol levels balanced as high cholesterol levels are closely linked to atherosclerotic renal artery stenosis. You can maintain a balanced cholesterol level by eating a diet rich in healthy fats (like those found in fish, nuts, and olive oil), fibers, and vegetables. You should also reduce your intake of processed foods, trans fats, and excessive sugar, as they will lower your cholesterol.
Regular physical activity also improves blood flow and helps maintain healthy kidney function by reducing the risks associated with hypertension and high cholesterol. We recommend that you aim for at least 30 minutes of moderate exercise, such as walking, swimming, or cycling, most days of the week. Staying active also helps in weight management, which is another critical factor in preventing renal artery stenosis.
Additionally, you should reduce stress for better cardiovascular outcomes. Engaging in stress-reducing practices such as mindfulness, yoga, or meditation can significantly improve cardiovascular outcomes. By managing stress, you help keep your blood pressure in check and reduce the risk of renal artery disease progressing.
It is also important to control your glucose levels. People with diabetes are at higher risk of developing both renal artery stenosis and other vascular complications. Therefore, keeping your blood sugar in a healthy range helps prevent the long-term complications that diabetes can cause, including damage to blood vessels and kidneys.
Do You Need to See a Doctor for Renal Artery Stenosis?
Renal artery stenosis (RAS) IS a condition where the arteries that supply blood to the kidneys become narrowed and can lead to serious complications such as chronic kidney disease, hypertension, and heart failure if left untreated. Therefore, it is important to detect this condition early and manage it effectively to prevent these outcomes. The main diagnostic methods for renal artery stenosis include Doppler ultrasound, CT Angiography, Magnetic Resonance Angiography (MRA), and Renal Angiography.
If you or a loved one is at risk for renal artery stenosis, it is important to consult a vascular specialist for proper screening and treatment. At our Center for Advanced Cardiac and Vascular Interventions (CACVI) in LA, we offer expert care in diagnosing and treating vascular conditions, including renal artery stenosis. Contact us now!
✓ Medically reviewed by
Dr. Vasim Lala
D.O., FACC, FSCAI, RPVI · Coronary, vascular and structural intervention
Trained at Mount Sinai in New York in advanced coronary, vascular and structural intervention. Focuses on minimally invasive heart and vascular procedures and on preventive cardiology, and writes for the American College of Cardiology.
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