Renovascular hypertension is high blood pressure caused by the hardening and thickening of the arteries that supply blood to the kidney.
What is going on in the body?
Arteries are tubes lined with smooth muscle through which blood flows in the outward direction from the heart. The inside lining of healthy arteries is smooth so that blood can flow through them easily. Over time, the arterial lining can become rough, and fatty substances called plaque can start to build up.
This narrows the arteries, and blocks the normal flow of blood to the kidneys. The kidneys (falsely) interpret this scenario as one of low blood volume, and so respond by releasing substances to increase the flow of blood. The kidneys also begin to retain salt and water. This will continue until normal blood flow to the kidneys resumes.
What are the causes and risks of the disease?
These people have a greater risk of developing renovascular hypertension:
- anyone with peripheral vascular disease, which is a condition that affects the small blood vessels
- anyone with diabetes, a disease in which the body cannot make insulin, so sugar builds up in the blood and urine
How is the disease diagnosed?
Diagnosis is made by looking at health records, and doing a physical exam and lab tests. Most people with this disease have very high blood pressure despite taking many drugs to control it. If they begin taking ACE inhibitors, however, they often develop low blood pressure or kidney failure.
Some tests that can be helpful in the evaluation of renovascular hypertension include:
measurement of the blood level of renin, a kidney hormone, which is generally elevated in renovascular hypertension
the captopril test, where captopril (i.e., Capoten) is given to see if the blood pressure drops
ACE inhibitor-stimulated renography, which is an X-ray of the kidney and its blood system, taken after the patient is given an ACE-inhibitor such as captopril
magnetic resonance arteriography (MRA, a special three-dimensional imaging using magnets). During this test, a group of pictures are taken of the arteries around the kidney. This information allows physicians to see the flow of blood to the kidneys and determine the location and amount of blood vessel blockage.
renal arteriogram (x-ray test in which dye is injected into the artery to make sure it is not blocked or narrowed). This test is used if a healthcare professional thinks a person has this disease, but the MRA did not give clear results, or if the professional needs a clearer picture of the blocked arteries.
What are the treatments for the disease?
- high blood pressure medicine
- angioplasty, which is a nonsurgical procedure to unclog a blocked artery
- stenting, a procedure that places a mesh tube into an artery to make it wider and hold it open for better blood flow
What happens after treatment for the disease?
It is most important to bring the blood pressure down to a normal level and to control any kidney disease. Blockage in the arteries may recur, and angioplasty or stenting may have to be done again.
How is the disease monitored?
Regular follow-up visits with the healthcare professional will be needed to check blood pressure and kidney function.