Renovascular hypertension

Renovascular hypertension is high blood pressure (greater than 140/80 mmHg) caused by renal artery disease. Normally, the kidneys regulate body fluid and blood pressure, as well as regulate blood chemistry and remove organic waste. Proper kidney function is disrupted, however, when the arteries that provide blood to the kidneys become narrowed, a condition called renal artery stenosis. When stenosis results in reduced blood-flow, the kidney compensates by producing hormones that increase blood pressure. This response is a healthy one under normal circumstances. But when the reduction in blood-flow is due to stenosis, blood pressure is increased unnecessarily.

High blood pressure caused by renal artery disease may be difficult to control with medication. The good news is that renovascular hypertension is one of the few identifiable and treatable causes of high blood pressure — a condition that, if left untreated, can lead to heart attack, stroke or kidney failure.

Primary hypertension is high blood pressure that has no apparent cause. Renovascular hypertension is the most common cause of secondary hypertension, high blood pressure that can be attributed to a specific cause. It is responsible for about 1 percent to 2 percent of the 50 million estimated cases of hypertension in the United States.

Clues that high blood pressure is being caused by renal artery stenosis include:

• Significant high blood pressure at a young age
• Stable hypertension that suddenly gets worse
• High blood pressure that occurs with impaired renal function
• High blood pressure in someone with an abdominal aortic aneurysm or disease of the coronary, carotid or the lower extremity arteries

Patients who have atherosclerosis in some other part of the body are 30 percent to 50 percent more likely to develop renal artery stenosis.

Renovascular disease can usually be diagnosed via duplex ultrasound scanning and other non-invasive tests. These include CT angiography and MR angiography. However, the definitive test is contrast angiography, a test that involves the injection of dye. If a blocked renal artery is discovered during an angiogram, treatment to open the artery may be performed during the same procedure.

The most common treatment for renovascular hypertension caused by renal artery stenosis is balloon angioplasty to open the artery followed by stent placement to keep it open. The procedures involve the placement of a catheter in an artery of the groin through a small puncture in the skin. A balloon is advanced to the affected renal artery where it is inflated, dilating the artery wall. A tube-like stent is then inserted to keep the artery open and the blood flowing freely. Patients usually stay in the hospital overnight and quickly resume normal activities.

Some patients may need open surgical repair of the renal arteries due to recurrent narrowing. During this open abdominal surgery, the artery is repaired using a graft from the aorta or some other healthy vessel.