Renal Artery Stenosis
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Renal artery stenosis occurs when one or more arteries supplying blood to the kidneys become narrowed. This constriction restricts the flow of oxygen-rich blood to the kidneys, which is essential for their proper function in filtering waste and regulating fluid levels in the body. Reduced blood flow can result in kidney tissue damage and elevated blood pressure throughout the body.
Symptoms
Renal artery stenosis frequently remains asymptomatic until it reaches an advanced stage. Often, the condition is detected incidentally during tests conducted for unrelated reasons. Additionally, your doctor may suspect an issue if you experience:
- Elevated blood pressure that starts unexpectedly or becomes worse on its own
- Elevated blood pressure that starts before 30 or beyond 50
Other signs and symptoms that may appear when renal artery stenosis worsens include:
- Fatigue
- Loss of appetite
- Nausea and vomiting
- Muscle cramps
- Headache
- Difficulty breathing
- Changes in urination frequency (either more or less often)
- Elevated protein levels in the urine or other signs of a kidney problem
- A worsening kidney function while you are receiving treatment for high blood pressure
- An excess of fluid and edema in the tissues of your body
- A heart failure resistant to treatment
- Difficulty controlling high blood pressure
- Alterations in the skin, like dry, itchy, or discolored (darker) skin
- A whooshing sound made by blood passing through a narrowed vessel (bruit), which your doctor can hear through a stethoscope placed over your kidneys
If you observe any ongoing signs or symptoms that worry you, it’s advisable to arrange an appointment with your doctor.
Causes
The primary culprits behind renal artery stenosis are:
- Buildup on renal arteries. Lipids, cholesterol, and other materials (plaque) have the potential to accumulate within and on the walls of your renal arteries, a condition known as atherosclerosis. Over time, these deposits may grow, solidify, impede blood flow, lead to kidney scarring, and ultimately result in artery narrowing. Atherosclerosis can develop in various regions of the body and stands as the primary cause of renal artery stenosis.
- Fibromuscular dysplasia. Fibromuscular dysplasia involves abnormal growth of the muscle within the artery wall, which typically initiates during childhood. In this condition, the renal artery may exhibit narrow segments interspersed with wider sections, creating a bead-like appearance in artery images. When the renal artery narrows significantly, the kidney may not receive adequate blood supply, potentially triggering early-onset hypertension. This can affect one or both kidneys. The precise cause of fibromuscular dysplasia remains unclear, although it appears to be more prevalent in women and may be congenital, possibly present from birth. Constrictions in the kidney arteries and fibromuscular dysplasia can affect not only the renal arteries but also other arteries in the body, leading to complications.
Occasionally, renal artery stenosis may develop due to other conditions, such as vascular inflammation or the growth of abdominal masses that compress the arteries supplying the kidneys.
Risk factors
The primary cause of renal artery stenosis is narrowed kidney arteries. Risk factors that increase the likelihood of narrowed arteries affecting your kidneys and other areas of your body include:
- Aging
- Obesity
- Diabetes
- High blood pressure
- High cholesterol
- Lack of exercise
- Early heart disease in the family
- Using tobacco products and smoking
Diagnosis
When making the diagnosis of renal artery stenosis, your doctor could start by:
- An examination of your past medical records
- A physical examination in which your doctor listens for noises that could indicate a constricted renal artery over the kidney regions with a stethoscope.
- Tests on your kidney function, blood pressure, and hormone levels that control blood pressure can all be performed with blood and urine.
The following imaging studies are frequently used to diagnose renal artery stenosis:
- Doppler ultrasound. Your doctor can observe and examine your kidneys and arteries with the use of high-frequency sound waves. This treatment also aids in the diagnosis and assessment of blood vessel blockages by your physician.
- Computed Tomography (CT) scan. An X-ray machine connected to a computer produces a detailed image during a CT scan that displays cross-sectional views of the renal arteries. To demonstrate blood flow, you can be given an injection of dye.
- Magnetic Resonance Angiography (MRA). MRA creates precise three-dimensional (3D) pictures of the kidneys and renal arteries using radio waves and powerful magnetic fields. During imaging, blood vessels are outlined by an injection of dye into the arteries.
- Renal arteriography. This particular kind of X-ray examination aids in the diagnosis of renal artery blockage by your doctor, who may use a balloon or stent to open the restricted portion. Your doctor uses a long, thin tube called a catheter to inject a dye into the renal arteries prior to taking an X-ray in order to better define the arteries and demonstrate blood flow. The major reason for doing this test is to see if you could also require the placement of a small tube, or stent, in your blood vessel to enlarge it.
Treatment
Renal artery stenosis treatment options include medication, lifestyle modifications, and kidney blood flow restoration surgery. Sometimes the best course of action is to combine many treatments. Your general health and symptoms may determine whether you require any special therapy or not.
Lifestyle changes
A healthy lifestyle that includes eating healthy foods and maintaining a diet low in salt, and obtaining regular physical exercise might help regulate blood pressure if it is moderately or severely raised.
Medication
Even when the primary cause of high blood pressure is renal artery stenosis, medication is frequently an effective treatment. It may take some time and patience to find the proper drug, or combination of medications.
The following are some drugs that are frequently used to treat high blood pressure brought on by renal artery stenosis:
- Angiotensin-Converting Enzyme (ACE) inhibitors and Angiotensin II Receptor Blockers (ARBs), which aid in blood vessel relaxation and prevent the production of or the effects of angiotensin II, a bodily substance that naturally narrows blood vessels.
- Beta blockers and alpha-beta blockers, which, depending on the specific medication, may work by widening your blood vessels or by slowing down and reducing the force of your heartbeats.
- Calcium channel blockers, may aid in blood vessel relaxation.
- Diuretics, commonly referred to as “water pills,” which aid in the body’s removal of extra water and salt
In the event that renal artery stenosis is caused by atherosclerosis, your doctor might additionally suggest aspirin and a cholesterol-lowering drug. The right drugs for you will depend on your unique circumstances.
Procedures
Some individuals might be advised to undergo a procedure aimed at reinstating blood flow through the renal artery, thereby enhancing blood circulation to the kidney. Clinical trials comparing medication with renal angioplasty and stenting for patients with moderate renal artery stenosis found no significant difference between the two treatment approaches in terms of reducing blood pressure and improving renal function.
Individuals who do not respond effectively to medication alone, have heart failure resistant to treatment, experience frequent fluid retention, or cannot tolerate medication should consider undergoing the procedure to reopen the artery.
Renal artery stenosis can be treated with the following procedures:
- Renal angioplasty and stenting. During this surgery, a device called a stent is inserted into your blood vessel to hold its walls open and improve blood flow, while also widening the restricted renal artery.
- Renal artery bypass surgery. In order to create a new path for blood to get to your kidneys, physicians graft a replacement blood vessel to the renal artery during a bypass treatment. This may occasionally entail joining the renal artery to a vascular that originates in another organ, like the spleen or liver. These procedures are typically carried out in cases where angioplasty proves unsuccessful or when additional surgical procedures become necessary.
