Renal hypertension, also called renovascular hypertension, is elevated blood pressure caused by kidney disease. It can usually be controlled by blood pressure drugs. Some people with renal hypertension can be helped by angioplasty, stenting, or surgery on the blood vessels of the kidney.
Causes of Renal Hypertension
When the kidneys receive low blood flow, they act as if the low flow is due to dehydration. So they respond by releasing hormones that stimulate the body to retain sodium and water. Blood vessels fill with additional fluid, and blood pressure goes up.
The narrowing in one or both renal arteries is most often caused by atherosclerosis, or hardening of the arteries. This is the same process that leads to many heart attacks and strokes. A less common cause of the narrowing is fibromuscular dysplasia. This is a condition in which the structure of the renal arteries develops abnormally for unclear reasons.
Symptoms of Renal Hypertension
Renal hypertension usually causes no symptoms. The narrowing in the arteries can't be felt. Unless it's dangerously high, high blood pressure causes no symptoms, either. Symptoms of severely elevated blood pressure include:
The vast majority of people with renal hypertension never experience these (or any) symptoms. High blood pressure is dangerous, partly because there are no symptoms, so organ damage can occur slowly without being recognized.
Renal hypertension can cause chronic kidney disease. This is a slow decline in kidney function. Until the condition is well advanced, chronic kidney disease also causes no symptoms.
Because there are usually no symptoms, a doctor may suspect renal hypertension when someone has uncontrolled high blood pressure despite multiple medications or has unexplained chronic kidney disease.
Treatments for Renal Hypertension
Medications are used first to try to control high blood pressure in renal hypertension. The most important blood pressure medications to treat renal hypertension include:
For most people with renal hypertension due to renal artery narrowing, medications can effectively control blood pressure. More than one blood pressure drug is often needed, however.
In some people with renal hypertension due to narrowing of the renal artery, even taking three or more medications every day may not adequately control blood pressure. In these situations, a procedure to improve blood flow to the kidneys may help.
Possible procedures include:
Angioplasty. A doctor threads a catheter through a large artery in the groin and advances it into the renal artery. A balloon is then inflated for a few moments. This widens the artery and improves blood flow.
Stenting. During angioplasty, a wire-mesh stent can be expanded inside the renal artery. The stent stays in place. This keeps the artery open after the balloon is removed. Research, however, has not shown that stenting is more effective than medication for renal hypertension.
Surgery. A surgeon can bypass the narrowed renal artery by sewing a healthy blood vessel next to it. Surgery is generally considered only when angioplasty and stenting are not possible.
Results of Treatment
For people whose blood pressure is not controlled with multiple medications or for those who can't tolerate blood pressure medication, surgery may be an effective fix for renal hypertension.
If a procedure is needed, renal artery stenosis is almost always treated by stenting or angioplasty. However, stenting/angioplasty has not been shown to be beneficial in most studies compared to medical management alone. Still, it may have a role for treatment in some people. Generally, procedures are more effective when only one kidney's artery is narrowed rather than both.