What is a renal stent?
A renal stent is a metallic expandable mesh tube, used to treat a narrowed renal artery. The artery may be narrowed by plaque within the aorta or renal artery, which supply the kidneys. This is called renal artery stenosis. It is normally caused by atherosclerosis. The stent acts as a scaffold in order to keep the artery open. This is a minimally invasive procedure and may be performed instead of open surgical endarterectomy or bypass.
Why treat renal artery stenosis?
A narrowed renal artery may result in kidney failure or high blood pressure (hypertension). Hypertension which is uncontrolled increases the risk of heart attack, congestive heart failure, stroke, kidney failure, peripheral arterial disease and aneurysm formation (blood vessel wall weakening).
How is renal artery stenosis diagnosed?
Ultrasound may demonstrate elevated velocities or abnormal waveforms in the renal arteries which would suggest renal artery stenosis. However, the study is often sub-optimal as the renal arteries are technically difficult to interrogate using ultrasound.
Non-invasive imaging, such as CT angiography may show narrowing of the renal arteries. The kidneys can be assessed and other organs such as the adrenal glands may also be viewed at this time, as alternative causes for high blood pressure.
The gold standard for looking at abnormalities of the renal arteries is by angiography. The diameter and degree of narrowing of the arteries can be assessed. Flow in the arteries and the size of the kidneys can also be ascertained.
How is renal artery stenting performed?
Renal artery stenting is performed by Interventional Radiologists: subspecialised doctors who are trained in performing minimally invasive procedures using state of the art medical imaging. A combination of ultrasound and Xrays are often used. A thin tube (catheter) is introduced into the arterial system. This may be from the groin, or the arm. The catheter is then steered to the renal artery. Once access to the renal artery is achieved, a stent is deployed in the narrowed segment, dilating and holding the walls of the artery open. The position of the stent is then confirmed with an injection of Xray dye. The procedure normally takes about 30 minutes.
How do I recover?
The procedure is normally performed in hospital as a day-only procedure. It is unusual to be kept overnight. The puncture site is normally sealed with a closure device. You will have to stay in hospital for 2-4 hours after the procedure. This is to ensure that there are no complications related to the puncture site and that you recover adequately from the sedation.
What should I do after the procedure?
In order to keep the stent open, certain medications are required in order to minimise the chances of the stent clotting or blocking off. Aspirin and "platelet inhibitors" are most commonly prescribed. It is important that these are taken and not ceased without medical advice. Lifestyle changes should also be continued in order to reduce the impact of atherosclerotic risk factors. This includes not smoking, reducing cholesterol, eating a healthy diet, controlling diabetes and regular exercise.