Renal refers to anything related to the kidneys. Renal arteries carry blood from the heart to the kidneys. They branch directly from the aorta (the main artery coming off the heart) on either side and extend to each kidney. These arteries take a very large volume of blood to the kidneys to be filtered.
The heart pumps out approximately 5 liters of blood per minute, and about 1-1.5 liters (25%) of the total volume of blood pumped by the heart passes through the kidneys every minute.
Renal artery stenosis (narrowing) is a decrease in the diameter of the renal arteries. The resulting restriction of blood flow to the kidneys may lead to impaired kidney function (renal failure) and high blood pressure (hypertension), referred to as renovascular hypertension, or RVHT ("reno" for kidney and "vascular" for blood vessel).
Renovascular hypertension is as likely to occur with bilateral stenosis (when arteries to both kidneys are narrowed) as with unilateral stenosis (when the artery to one kidney is narrowed). The decreased blood flow to the kidneys impairs renal function. Renal artery stenosis may cause renal failure in some patients. There is no predictable relationship between renal failure and renal artery stenosis. Some patients have very severe bilateral stenosis and normal renal function. Most cases of renal failure are related to diabetes, hypertension, glomerular sclerosis, contrast nephropathy, drug toxicity and other causes.