14868 Renal Artery Stenting

Overview

A renal artery stent is a tiny mesh tube placed inside one of the arteries that carries blood to your kidney. The renal arteries are the two blood vessels that supply your kidneys (renal means 'to do with the kidneys'). When one of these arteries becomes narrowed — a problem called renal artery stenosis — less blood reaches the kidney. A stent is gently opened up inside the narrowed section to hold the artery open so blood can flow more freely. The procedure is usually done through a small tube inserted in a blood vessel in the groin or wrist, so it does not involve a large cut. It is not a cure for everyone, but it can help protect the kidney and sometimes helps blood pressure that has been hard to control.

Narrowing of the kidney arteries is a reasonably common finding, especially in people who already have hardening of the arteries elsewhere in the body. Having a stent placed is much less common — it is offered only to selected people after careful testing.

It most often affects older adults who have hardening of the arteries (atherosclerosis) and other heart or circulation problems. It can also affect younger adults, more often women, who have a condition called fibromuscular dysplasia, where the artery wall develops unusual fibrous tissue. Children can be affected but this is rare.

Symptoms

Common symptoms

• Often no symptoms at all — the narrowing may be found during tests done for another reason
• High blood pressure that is difficult to control, or that suddenly gets worse
• High blood pressure starting before the age of about 30 or after the age of about 55
• A drop in kidney function found on blood tests, especially after starting a blood pressure medicine
• Swelling (fluid build-up) in the legs, or an abnormal sound the doctor hears through a stethoscope over the abdomen
• Feeling more tired than usual, or generally unwell, when kidney function is affected

Symptoms in children

• High blood pressure found during a routine check, sometimes with headaches or nosebleeds
• Slower growth or poorer weight gain than expected
• Irritability or tiredness in a young child who cannot describe symptoms
• In many children there are no symptoms and the problem is found on tests

Symptoms in older adults

• Worsening blood pressure control despite several medicines
• Kidney function that gets worse over time, or after certain blood pressure medicines are started
• A shrinking kidney seen on a scan
• Symptoms of heart or circulation disease elsewhere, such as leg pain when walking or chest discomfort
• Sudden shortness of breath from fluid build-up in the lungs — this needs urgent medical help

Causes

Main causes

• Hardening of the arteries (atherosclerosis): fatty, calcium-rich plaques build up in the artery wall and narrow the channel blood flows through
• Fibromuscular dysplasia: a condition where fibrous tissue grows in the artery wall, usually in younger women, causing narrowing
• Less common causes include tears in the artery wall (dissection), bulging of the artery (aneurysm), inflammation of blood vessels, or previous radiotherapy to the abdomen
• Sometimes pressure from outside the artery, or a congenital (from birth) shape difference, can narrow it

Risk factors

• Smoking or long-term exposure to second-hand smoke
• High blood pressure
• High cholesterol or other blood fats
• Diabetes
• Older age and being male for the atherosclerosis type
• Being a younger woman for the fibromuscular dysplasia type
• Existing heart, stroke or leg artery disease
• Being overweight and not being physically active
• A family history of heart or blood vessel disease

When to see a doctor

See a doctor urgently if:

• Blood pressure that stays very high despite your medicines, or readings much higher than your usual
• A sudden fall in how much urine you pass, or blood in your urine
• New breathlessness, especially when lying flat, or swelling that is getting worse quickly
• Fever, spreading redness or severe pain at a procedure site

Book a routine appointment if:

• Blood pressure that needs more and more medicines to keep in check
• Your doctor has mentioned a change in your kidney blood tests
• You have been told you have a narrowed kidney artery and want to discuss options
• You have questions about a stent you already have, your follow-up, or your medicines

Diagnosis

Your doctor starts by taking your history, checking your blood pressure in both arms and listening over your abdomen with a stethoscope. Blood and urine tests show how well your kidneys are working. If a narrowed kidney artery is suspected, imaging is used to look at the artery. The choice of scan depends on your kidney function, your other health conditions and what is available locally — some scans use a dye (contrast) that your kidneys have to clear, so your team will plan this carefully.

Tests that may be done

• Blood pressure checks, sometimes over 24 hours or at home
• Blood tests for kidney function, salts and cholesterol
• Urine tests to check for protein or blood
• Ultrasound scan with Doppler, which shows blood flow through the artery without any dye
• CT angiography or MR angiography — detailed 3D pictures of the arteries, usually with contrast dye
• Catheter angiography, where dye is injected through a thin tube; this is sometimes done at the same time as treatment
• A kidney scan to see how much each kidney is contributing to overall kidney function

What to expect at your appointment

You may have several appointments and more than one scan before any decision is made. Some scans take only a few minutes; others need you to lie still for 20–40 minutes. If a scan uses dye, you may be asked to drink plenty of water afterwards and to have a blood test a day or two later to check your kidneys. Your specialist team will explain each step and give you time to ask questions before you agree to anything.

Treatment

Treatment has three parts: protecting your heart and blood vessels in general, controlling blood pressure and kidney health with medicines and lifestyle, and — for a selected group of people — opening the narrowed artery. Renal artery stenting is usually done by passing a thin, flexible tube (catheter) through a small puncture in the groin or wrist and guiding it to the kidney artery. A small balloon is inflated to widen the narrowing and the mesh stent is left in place to keep the artery open. You will usually be awake but relaxed, with the skin numbed, and you can often go home the same day or the next. Sometimes the decision is to watch and wait rather than to place a stent.

Self-care at home

• Take your medicines exactly as prescribed and do not stop them on your own, even if you feel well
• Check your blood pressure at home if your team asks you to, and keep a simple record to bring to appointments
• Stop smoking — this is the single most helpful thing you can do for your arteries, and your doctor can offer support
• Stay well hydrated, especially if your team has advised extra fluids around a scan or procedure
• Attend your follow-up appointments and blood tests, even when you feel fine
• Tell any doctor, dentist or nurse that you have a kidney stent before scans, procedures or operations

Medical treatments

Most people are treated first with medicines that lower blood pressure, medicines that lower cholesterol, medicines that make the blood less likely to clot, and treatment for diabetes if present. These are chosen and adjusted by your doctor to suit your kidneys and your other conditions. Your care team will also look at the rest of your heart and circulation, because narrowed kidney arteries usually sit alongside wider blood vessel disease. Never change or stop any medicine without speaking to your prescriber first.

When is surgery considered?

A stent may be suggested when blood pressure stays high despite several medicines, when kidney function is getting worse, when one kidney is shrinking, or when there has been a sudden build-up of fluid in the lungs linked to the narrowed artery. It may not be recommended if the kidney is already very small and not working, if the risks of the procedure are high, or if the narrowing is not thought to be causing your problems. Your team will explain the reasons for their advice in your own case.

Living with this condition

Most people get back to normal daily activities within a few days. You may have a small bruise or lump where the tube went in, and you should avoid heavy lifting, straining or vigorous exercise for about a week or as advised. Ask your team when you can drive, bathe, or return to work — this varies from person to person. Keep taking your medicines and keep your follow-up appointments, which may include blood tests and occasionally a scan to check the stent.

Lifestyle tips

• Eat more vegetables, fruit, whole grains, beans and fish, and cut down on salt and heavily processed food
• Aim for regular activity such as walking, building up gradually; ask your team what is safe for you
• Keep to a healthy weight and cut back on alcohol
• Stop smoking and avoid smoky places; ask about local stop-smoking support
• Get enough sleep and find ways to manage stress, such as breathing exercises or a hobby you enjoy
• Keep diabetes and cholesterol well controlled if you have them

Diet and exercise

A heart-friendly eating pattern helps both your kidneys and your arteries. Try to keep salt low — many people find that cooking from scratch and reading labels helps most. Choose water rather than sugary drinks. For exercise, gentle and regular beats occasional and extreme: a brisk walk most days is a great start, and your doctor can advise on any limits. If you have kidney disease, ask whether you need any specific dietary advice, as some people are advised about potassium, phosphate or protein.

Mental health and emotional wellbeing

Being told you have a blood vessel problem, and having a procedure, can bring worry, low mood or poor sleep. This is very common and nothing to be ashamed of. Talking to a partner, friend, GP or counsellor often helps. If low mood, anxiety or distressing thoughts continue for more than a couple of weeks, please tell your doctor — support is available, and you deserve it.

Prevention

You cannot control every risk factor, but you can lower your chances of the atherosclerosis type of narrowed kidney artery. Not smoking, keeping blood pressure and cholesterol in a healthy range, staying active, eating well and managing diabetes are all proven ways to protect your arteries. The fibromuscular dysplasia type is not caused by lifestyle and cannot be prevented, but it can be monitored.

Screening programmes

There is no routine national screening programme for narrowed kidney arteries. Blood pressure is checked routinely in most health systems, and that is often how the problem is first suspected. If you have several risk factors, or a family history of early heart or blood vessel disease, ask your doctor whether your blood pressure, cholesterol and kidney function should be checked.

Complications

If left untreated

• Blood pressure that becomes harder and harder to control
• Gradual loss of kidney function, and in some people kidney failure over time
• Shrinking of the affected kidney
• Sudden fluid build-up in the lungs, which is a medical emergency
• Higher risk of heart attack, stroke and other circulation problems, because the same process affects blood vessels throughout the body

Long-term outlook

The outlook is often good. Many people stay stable for years with medicines and lifestyle changes, and a stent helps some people keep better blood pressure control or protect kidney function. Stents do sometimes narrow again over time, so follow-up matters — but this is checked for and managed. Your own outlook depends on your overall health, so the best guide is a frank conversation with your specialist team about your particular case.

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