Renal Artery Stenosis
Renal artery stenosis (RAS) is a medical condition in which the arteries that supply pure blood to the kidneys become narrow. As a result the kidneys cannot function properly and the wastes get accumulated in the body. If RAS is not treated properly it can result in high blood pressure, edema of the body parts and kidney damage.
Usually, patients with RAS do not exhibit any symptoms in the initial stages. However, symptoms become evident as the disease progresses. The following signs and conditions are associated with RAS:
- Decrease in kidney function
- Fluid retention
- Uncontrolled hypertension
- Swelling of the feet and ankles
- Increase in the urinary proteins
If the condition has progressed, then the symptoms include:
- Darkening of skin
- Edema of the face and other body parts
- Changes in the urine output
- Muscle cramps
- Unintentional weight loss
- Nausea and vomiting
Renal artery stenosis occurs due to the deposition of fats and cholesterol in the arteries supplying the kidneys. This leads to the hardening of the arterial walls. Over a period the arteries become narrow and the blood flow decreases.
In some cases, RAS occurs as a result of fibromuscular dysplasia. In this condition the muscles outside the arteries grow excessively and create pressure on the arteries leading to their narrowing.
Other less common causes include:
- Swelling of the blood vessels, i.e. vasculitis
- Growth of tumors on the nerve tissue, i.e. neurofibromatosis
- Unusual growths which put pressure on the kidneys
Although RAS can develop in both the genders, women are at higher risk of developing fibromuscular dysplasia and RAS. The other factors which make a person more prone to RAS are as follows:
- Advancing age
- Vascular diseases such as high blood pressure, peripheral artery disease and coronary artery disease
- Abnormal cholesterol levels
- Chronic kidney disease
- Use of tobacco
When to consult the doctor?
Visit the doctor if there are any abnormal symptoms of blood pressure or fluid retention. The doctor will check the kidney function and test for RAS.
After knowing the symptoms, the doctor performs a physical examination of the patient and takes the necessary history of the patient. If the doctor suspects renal artery stenosis from these details, then further testing may be ordered to confirm the cause. The tests may include:
- Blood and urine tests to assess the kidney function
- Ultrasound to see if there are any abnormalities in the size and structure of the kidneys
- Doppler ultrasound to measure the blood flow rate in the arteries of the kidneys
- Other imaging studies such as computed tomography (CT) and magnetic resonance imaging (MRI) to give a more detailed image of the kidneys and the blood vessels
Treatment options include medicines, lifestyle changes and surgical procedures. Usually, a combination of treatments is effective.
Medications given to treat high blood pressure are highly effective. Some of the commonly used medicines for treating RAS include:
- Calcium channel blockers to relax the blood vessels
- Beta-blockers reduce the heart beat and work load on the heart. They may also cause widening of the blood vessels
- Diuretics eliminate excess fluids by removing excess sodium and water from the body
- Angiotensin converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs) relax the blood vessels
If atherosclerosis is the cause for RAS then drugs such as aspirin and cholesterol-lowering agents are given.
If complications such as worsening of kidney function or pulmonary edema occur then certain surgical procedures are needed to improve the blood supply to the kidney. These include:
Renal arteries bypass surgery in which a new route is created for supplying blood to the kidneys
Renal angioplasty and stenting in which a device is placed in the narrowed blood vessel to allow better blood flow
Certain life style changes may help in managing RAS. They include:
- Eating healthy foods
- Reducing the salt intake in the food
- Maintaining healthy body weight
- Being physically active
- Reducing the intake of alcohol and caffeinated beverages
- Practicing yoga or mind-calming activities to reduce stress