Renal artery stenosis is the narrowing of one or more arteries that carry blood to your kidneys (renal arteries).
Narrowing of the arteries prevents normal amounts of oxygen-rich blood from reaching your kidneys. Your kidneys need adequate blood flow to help filter waste products and remove excess fluids. Reduced blood flow may increase blood pressure in your whole body (systemic blood pressure or hypertension) and injure kidney tissue.
Renal artery stenosis care at Mayo Clinic