What causes Renal Artery Stenosis ?
About 90 percent of RAS is caused by atherosclerosisclogging, narrowing, and hardening of the renal arteries.2 In these cases, RAS develops when plaquea sticky substance made up of fat, cholesterol, calcium, and other material found in the bloodbuilds up on the inner wall of one or both renal arteries. Plaque buildup is what makes the artery wall hard and narrow.
                
Most other cases of RAS are caused by fibromuscular dysplasia (FMD)the abnormal development or growth of cells on the renal artery wallswhich can cause blood vessels to narrow. Rarely, RAS is caused by other conditions.