Renal Artery Disease
Like other peripheral artery diseases, renal artery disease is caused by the buildup of plaque in the arteries that lead to the kidneys. Plaque is made up of fats and cholesterol, and as it accumulates in the renal arteries, it causes the arteries to stiffen and narrow, which blocks the flow of blood to the kidneys. Obstructions (blockages) in the renal arteries, known as renal artery stenosis, can cause poorly controlled high blood pressure, congestive heart failure, and kidney failure.
Renal artery disease most often is related to peripheral artery disease (atherosclerosis in arteries outside the heart) or coronary artery disease. Atherosclerotic renal artery disease is the most common form of this condition, accounting for more than 80 percent of all renal artery disease. The balance is generally caused by fibromuscular dysplasia, a congenital disorder that causes the thickening of the artery walls without plaque build-up.
The kidneys play an important role in regulating blood pressure by secreting a hormone called renin. If the renal arteries are narrowed or blocked, the kidneys cannot work effectively to control blood pressure. Persistent or severe high blood pressure is a common symptom of renal artery stenosis.
High blood pressure that is not controlled by medications and lifestyle changes, including diet and exercise, maybe a symptom of renal artery disease. Symptoms of renal artery disease may also include episodes of fluid retention or congestive heart failure. In some cases, renal artery disease may be entirely asymptomatic (not associated with any symptoms).
In severe cases, renal artery disease may lead to kidney failure. Symptoms of kidney failure include weakness, shortness of breath and fatigue.
Many of the risk factors for renal artery disease are the same as those for atherosclerosis in other parts of the body, such as coronary artery disease and peripheral arterial disease. Risk factors for renal artery disease include:
- age over 50
- high cholesterol
- high blood pressure
- family history of coronary artery disease
- family history of peripheral arterial disease
- family history of renal artery disease
Renal Artery Ultrasound
A renal artery ultrasound evaluates blood flow to the kidneys through the renal artery and is often used to diagnose renal artery stenosis. Renal artery stenosis is a narrowing of arteries that carry blood to one or both of the kidneys. Most often seen in older people with atherosclerosis (hardening of the arteries), renal artery stenosis can worsen over time and often leads to hypertension (high blood pressure) and kidney damage.
Untreated renal artery disease gets progressively worse and can lead to kidney failure. Like treatment for heart disease, there are many treatments available for renal artery disease. The right treatment for an individual depends on the severity of the disease and the individual’s medical history.
All patients with renal artery disease require treatment for cardiovascular risk factors (such as high blood pressure, high cholesterol, diabetes) and lifestyle changes such as weight reduction, smoking cessation, exercise and a low-salt and low-fat diet. Medication to lower blood pressure is an important part of treatment, along with careful monitoring of the response to the blood pressure medications to be sure the blood pressure is lowered to the treatment goal. Regular follow-up every 4 to 6 months will be part of the treatment plan so your physician can monitor your condition.
For some patients with significant narrowing of the renal arteries, particularly patients with narrowed areas in the renal arteries on both sides of the body, or those with severe symptoms, a procedure may be recommended to open up the blocked arteries to restore circulation. In some cases, opening the blocked arteries may improve kidney function and may improve the control of high blood pressure. Not surprisingly, the techniques used to open blocked renal arteries are very similar to those used to treat blocked coronary arteries.
A small catheter – a long, thin tube – carrying a tiny balloon is inserted through a small puncture in the groin and guided by X-ray to the kidney artery. When the catheter is guided to the narrowed part of the artery, the balloon is inflated. As it expands, it compresses the plaque against the artery walls, re-opening the vessel for blood to flow through. Once the artery is open, the physician may insert a stent at the site to keep the artery open and support the arterial wall.
With the development of new and improved types of stents, angioplasty with stenting is the preferred treatment for renal artery disease. But, in certain cases, surgical treatment may be necessary to restore blood flow to the kidney and preserve kidney function.