Introduction
Renal artery stenosis is the constriction of the blood vessels carrying blood to the kidneys. This condition is mostly seen in elders with atherosclerosis or clogging and hardening arteries. In such cases, plaque or a sticky substance made up of fat, cholesterol, and calcium is found in the blood deposits in the inner wall of the renal blood vessels. This deposition of plaque makes the blood vessels hard and narrow. Some other cases of renal artery stenosis are caused by fibromuscular dysplasia (FMD) - an abnormal cellular growth in the kidney blood vessels, leading to the narrowing of the blood vessels. In due course of time, renal artery stenosis can deteriorate and lead to high blood pressure, eventually damaging the kidneys.
Who Can Develop Renal Artery Stenosis?
Anyone who has atherosclerosis has the potential to develop renal artery stenosis.
Other risk factors include:-
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High blood pressure.
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Higher cholesterol levels.
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Smoking.
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Insulin resistance.
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Diabetes.
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Old age.
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Overweight or obese.
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Sedentary lifestyle.
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Food high in fat, sodium, or sugar.
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A man above forty-five or a woman above fifty-five years of age.
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A family history of heart disease.
The risk factors of the condition caused by fibromuscular dysplasia are unknown, but it is more common in people aged 25 to 50. Fibromuscular dysplasia can affect many people in a family, thus indicating its genetic involvement.
What Causes Renal Artery Stenosis?
Two factors primarily cause renal artery stenosis:
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Atherosclerosis - Deposition on the kidney blood vessels or plaque is a deposit made up of fat cells, cholesterol, and other substances that can build up on the walls of the kidney blood vessels. With the due course, these deposits harden, reducing the blood flow, and causing scarring of the kidneys and narrowing of the blood vessels. As a result, atherosclerosis is one of the most common causes of renal artery stenosis.
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Fibromuscular Dysplasia - In this condition, the growth of the muscular wall of the kidney blood vessels are compromised. It often starts during childhood. As a result, the kidney blood vessel has alternate narrow and wider sections giving the appearance of a bead. Due to the constriction of the blood vessels, blood flow to the kidneys is hampered. This can happen to both kidneys leading to an increase in blood pressure at a very young age. The cause of the condition is unknown, but it is more common in women and might have a genetic predisposition. This narrowing of the arteries and fibromuscular dysplasia can also affect other blood vessels in the body and give rise to complications. In rare circumstances, renal artery stenosis can result from other conditions, such as inflammation of the blood vessels or an abdominal growth that presses the kidney blood vessels, causing stenosis.
What Are the Signs and Symptoms of Renal Artery Stenosis?
Renal artery stenosis does not show any specific symptom until it has advanced.
The symptoms include:-
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A sudden increase in blood pressure without any possible explanation.
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High blood pressure begins before the age of thirty or after the age of fifty.
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High blood pressure is difficult to bring down.
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Bruit - A whooshing sound is heard as the blood flows through a narrow blood vessel.
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An increase in the urine protein level and other signs of complicated kidney function.
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Deterioration of kidney function during treatment for high blood pressure.
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Edema - Fluid deposition and swelling of the body.
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Heart failure due to treatment resistance.
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Increased or decreased urination.
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Drowsiness or tiredness.
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Itching or numbness of the body.
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Dryness of skin.
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Loss of weight.
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Loss of appetite.
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Nausea and vomiting.
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Problems with falling asleep.
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Difficulty in concentration.
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Dark skin.
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Muscular cramps.
How Is Renal Arterial Stenosis Diagnosed?
Most of the time, renal arterial stenosis is detected incidentally during the diagnosis and treatment of other conditions. In case renal arterial stenosis is suspected, a couple of diagnostic tests are performed.
They are:
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Physical Examination - A thorough examination is carried out to check blood pressure, swelling in the arms or legs, and breathing rate. The blood flow through the kidney blood vessels can be heard with the help of a stethoscope.
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Kidney Function Tests - To understand how well the kidneys are working.
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Blood and Urine Tests - To test protein, creatinine, nitrogen, and other waste levels. An increase in these parameters indicates that the kidneys are not effectively filtering waste.
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Imaging Scans - Several imaging scans, such as renal scans, duplex ultrasounds, computerized tomographic angiography, or magnetic resonance angiogram, can evaluate the blood flow of the kidneys.
How Is Renal Arterial Stenosis Treated?
Treating renal arterial stenosis includes a combination of lifestyle modifications, medications, and surgery.
Lifestyle Changes - Certain changes should be made to promote healthy blood vessels. Ways to avoid plaque from building up in the blood vessels include:
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Exercise.
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Maintaining a healthy body weight.
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Eating healthy.
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Quitting smoking for the health of the kidneys.
Medications - Medications are prescribed to lower blood pressure and slow the rate of progression of kidney disease. Medications such as:-
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ACE Inhibitors - Angiotensin-converting enzymes and ARBs- Angiotensin receptor blockers have been found to slow the progression of kidney disease.
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Diuretics can be prescribed to help the kidneys remove fluid from the blood.
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Blood thinners like aspirin can be taken so that blood flows easily through the blood vessels.
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Statins - Cholesterol-lowering medication can be prescribed.
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Beta Blockers and Calcium Channel Blockers can be taken to reduce high blood pressure.
Surgery - Surgery has been used to treat renal artery stenosis due to atherosclerosis, but the outcomes were not good. However, surgery for renal artery stenosis caused by fibromuscular dysplasia is promising.
Angioplasty and Stenting - A catheter or thin tube is inserted into the narrow blood vessel. A tiny balloon is inflated inside the blood vessel to widen it. Next, a stent- a small mesh tube is placed within the blood vessel to keep it open and help the blood flow in the kidney.
Renal Artery Bypass Surgery - The blood flow is rerouted to the kidneys by bypassing the blocked renal artery.
Renal Endarterectomy - The narrowed renal artery is opened, and plaque is removed.
Conclusion:
Renal artery stenosis (RAS) occurs when the kidney blood vessels narrow. Atherosclerosis is the common cause leading to RAS. It can lead to various health problems like high blood pressure, chronic kidney disease, or kidney failure. Changes in lifestyle, medications, and surgery are the treatments for renal artery stenosis.
