The renal arteries are the vessels that carry blood to your kidneys. Renal artery stenosis occurs when one or both of these arteries are narrowed or blocked, which prevents the normal amount of oxygen-rich blood from being delivered to the kidneys. Your kidneys need adequate blood flow in order to filter out waste products and remove excess fluids from the body. When blood flow is reduced, this may increase the blood pressure of the whole body and result in injury to the tissues of the kidney. This can often be a silent killer, but without diagnosis the elevated blood pressure can cause numerous medical problems such as stroke, cardiac problems, aneurysms, and aortic dissections.
Why Do I Have Renal Artery Stenosis?
Arteries are generally smooth and unobstructed on the outside, but as someone ages they are at an increased risk of developing atherosclerosis or hardening of the arteries. As plaque builds up on the walls of the arteries, they narrow and stiffen. Over time, these blockages cause decreased blood flow to the area they are meant to supply blood. In this instance, the renal arteries.
There are many factors that can contribute to putting someone at risk of developing renal artery stenosis:
- Fibromuscular dysplasia
- Female gender
- Injury, surgery, or infection
- Inflammatory diseases
- Tumors or aneurysms
- High cholesterol
- High blood pressure
- Obesity or physical inactivity
- Smoking or use of tobacco products
- History of heart disease
How Is It Diagnosed?
In order to confirm diagnosis, the physician uses a combination of physical examination, review of medical history, as well as testing. Oftentimes, there are not many symptoms if any until the disease has progressed significantly. Diagnosis is generally confirmed by the following testing in conjunction with sign and symptoms review:
- Diagnostic angiogram (arteriogram): a thin, flexible tube is inserted into the artery and dye is injected under x-ray imaging to note any areas of narrowing, blockage, or aneurysm.
- Duplex ultrasound: can check blood flow and the structure of renal veins and arteries.
- Venography: using a small amount of a radioactive substance, this test can check the structure and function of the kidneys.
- MRA or CTA imaging: either form of imaging utilizes contrast dye to visualize areas of narrowing or blockage in the kidney arteries.
What Are My Treatment Options for Renal Artery Stenosis?
Treatment is dependent on your overall health and the symptoms experienced, but usually involves lifestyle changes, medication, or medical procedures. Oftentimes a combination of these therapies is the best option for management. Lifestyle modifications would include quitting smoking, trying to maintain a healthier weight, and getting regular exercise such as walking at least 30 minutes, 3 times a week. Also, it is very important to control other risk factors, by taking the appropriate prescribed medications to control blood pressure, cholesterol, and diabetes.
Medications prescribed by your vascular surgeon may include:
- ACE inhibitors or ARBs: helps relax your blood vessels and block the effects of a naturally occurring body chemical called angiotensin converting enzyme II, which narrows blood vessels
- Diuretics: help eliminate excess water from the body
- Beta blockers: make your heart beat slower and more effectively, and can widen and dilate the blood vessels
- Calcium channel blockers: relaxes blood vessels
- Statin drugs: these will help keep your cholesterol levels better controlled, preventing further plaque buildup in your arteries
In severe cases of renal artery stenosis, lifestyle modifications and medications may not be enough to help with symptoms. In this instance, the vascular surgeon will determine the best surgical or minimally invasive treatment that is best for you. This will depend on your overall health, presence of other conditions, and the location and extent of blockages.
- Angioplasty and Stenting: This is a minimally invasive procedure that involves inserting a long, thin flexible tube called a catheter through a small puncture over an artery in your arm or groin. Under x-ray guidance, this catheter is directed towards the blockage in the leg. A special balloon at the end of the catheter is deployed and deflated several times in order to compress the plaque against the walls of the artery. This widens the opening of the blood vessel, so blood is able to flow freely through it. In some instances, a mesh-like metal tube called a stent may be placed within the artery to keep it open. These procedures can be performed outpatient, with only a short 2 to 4-hour recovery period before the patient can go home.
- Bypass surgery: The surgeon will use either a synthetic cylinder-like tube called a graft or one of your own veins to reroute your blood flow around the renal artery blockage. The vein or graft is sewn above and below the area that is blocked, restoring blood flow to the tissues. This procedure requires a hospital stay of up to 5 days.
- Renal Artery Endarterectomy: The surgeon surgically removes the build-up of fats, cholesterol, and other substances (plaques) from the renal arteries.
How Can I Prevent Renal Artery Stenosis from Happening?
Renal artery stenosis is a phenomenon of atherosclerosis and hypertension that is called renovascular hypertension when it affects the blood supply to the kidneys. Renal artery stenosis is in the group of atherosclerotic diseases that can be prevented by mitigating these vascular diseases.
- Smoking cessation.
- Performing physical activity most days most days of the week.
- Lose weight and prevent obesity if overweight.
- Treat dyslipidemia with alterations in diet, exercise, and statins, if necessary. Goals of therapy should be: total cholesterol <200; LDL-C <130; and triglycerides <150.
- Manage hypertensions via diet, weight loss, and antihypertensive medications when necessary.
- Avoid hyperglycemia, especially diabetics.
In patients with significant stenosis, prevention of further damage to the arteries and/or kidney(s) calls for one of three general approaches:
- Medical therapy alone.
- Renal angioplasty percutaneously, usually with stent placement, in addition to medical therapy.
- Surgical revascularization in combination with medical therapy.