Renal artery stenosis is a narrowing of the arteries that supply blood to the kidneys. Any condition that leads to a narrowing of the blood vessels can cause RAS.
The most common cause of renal artery stenosis is atherosclerosis. Atherosclerosis is a condition caused when plaque (made up of cholesterol, fatty substances and calcium) builds up in the walls of arteries causing them to stiffen and, over time, narrow. The same process narrows blood vessels to the heart and brain increasing the risk of heart attack and stroke.
Less common causes include fibromuscular dysplasia (FMD), a disease typically affecting young women. It causes an abnormal cell or tissue buildup in the wall of the artery supplying the kidney causing it to narrow. Other, less common conditions causing a decreased blood flow to the kidney are inflammation of arteries (vasculitis) and external compression of the artery due to a mass in the abdomen.
Renal artery stenosis symptoms typically are secondary to high blood pressure, excess salt and water retention, and worsening kidney function. Unfortunately, people with high blood pressure often do not have symptoms, or the signs may be very subtle. These may include a feeling of fatigue or lack of energy, ringing in the ears, headaches, visual changes, nausea/vomiting or even nose bleeds.
A new diagnosis of high blood pressure under the age of 30 or sudden worsening of previously well-controlled blood pressure should raise suspicion of renal artery disease. Difficulty in controlling the blood pressure despite multiple medicines and lifestyle changes also may imply renal artery disease.
Over time, renal artery stenosis causes kidney function to deteriorate because of poor blood supply. A significant increase or decrease in urination, unintentional weight loss, loss of appetite, drowsiness, difficulty concentrating, muscle cramps, nausea and fluid retention can indicate worsening renal function.
Excess fluid retention in the body may cause swelling in the legs or abdomen, shortness of breath or fatigue. Other organs may be affected, such as the heart and brain. This can lead to heart failure from a thickening of the heart muscle, or stroke from damage to the brain's blood vessels due to long-term high blood pressure. Some patients may not experience any symptoms until the very advanced stages of the disease. Therefore, routine follow-up health visits are needed for early diagnosis.