user: What are the treatments for Renal Artery Stenosis ?

assistant: Treatment for RAS includes lifestyle changes, medications, and surgery and aims to
                
- prevent RAS from getting worse  - treat RVH  - relieve the blockage of the renal arteries
                
RAS that has not led to RVH or caused a significant blockage of the artery may not need treatment. RAS that needs to be treated, also called critical RAS, is defined by the American Heart Association as a reduction by more than 60 percent in the diameter of the renal artery.1 However, health care providers are not exactly sure what degree of blockage will cause significant problems.
                
Lifestyle Changes
                
The first step in treating RAS is making lifestyle changes that promote healthy blood vessels throughout the body, including the renal arteries. The best ways to keep plaque from building up in the arteries are to exercise, maintain a healthy body weight, and choose healthy foods. People who smoke should quit to help protect their kidneys and other internal organs.
                
Medications
                
People with RVH may need to take medications thatwhen taken as prescribed by their health care providerlower blood pressure and can also significantly slow the progression of kidney disease. Two types of blood pressure-lowering medications, angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs), have proven effective in slowing the progression of kidney disease. Many people require two or more medications to control their blood pressure. In addition to an ACE inhibitor or an ARB, a diuretica medication that helps the kidneys remove fluid from the bloodmay be prescribed. Beta blockers, calcium channel blockers, and other blood pressure medications may also be needed. Some people with RAS cannot take an ACE inhibitor or ARB due to the effects on the kidneys. People with RAS who are prescribed an ACE inhibitor or ARB should have their kidney function checked within a few weeks of starting the medication.
                
A cholesterol-lowering medication to prevent plaque from building up in the arteries and a blood-thinner, such as aspirin, to help the blood flow more easily through the arteries may also be prescribed.
                
Surgery
                
Although surgery has been used in the past for treatment of RAS due to atherosclerosis, recent studies have not shown improved outcomes with surgery compared with medication. However, surgery may be recommended for people with RAS caused by FMD or RAS that does not improve with medication. Different types of surgery for RAS include the following. The procedures are performed in a hospital by a vascular surgeona doctor who specializes in repairing blood vessels. Anesthesia is needed.
                
- Angioplasty and stenting. Angioplasty is a procedure in which a catheter is put into the renal artery, usually through the groin, just as in a catheter angiogram. In addition, for angioplasty, a tiny balloon at the end of the catheter can be inflated to flatten the plaque against the artery wall. A small mesh tube, called a stent, may then be positioned inside the artery to keep plaque flattened and the artery open. People with RAS caused by FMD may be successfully treated with angioplasty alone, while angioplasty with stenting has a better outcome for people with RAS caused by atherosclerosis.  - Endarterectomy or bypass surgery. In an endarterectomy, the plaque is cleaned out of the artery, leaving the inside lining smooth and clear. To create a bypass, a vein or synthetic tube is used to connect the kidney to the aorta. This new path serves as an alternate route for blood to flow around the blocked artery into the kidney. These procedures are not performed as often as in the past due to a high risk of complications during and after the procedure.