ConditionKidneys & urinary tract
Renal Artery Stenosis
Renal artery stenosis is narrowing of one or both arteries that carry blood to the kidneys. The kidneys respond to reduced blood flow by releasing hormones that raise blood pressure, so it often causes high blood pressure that is severe or hard to control, and it can gradually damage kidney function. In older adults the cause is usually atherosclerosis; in younger women it is often fibromuscular dysplasia. Most people are treated with blood pressure medicines and statins; angioplasty helps selected cases.
Also called: Renovascular disease, renovascular hypertension, renal artery narrowing, atherosclerotic renal artery stenosis
At a glance
- What it is
- Narrowing of the renal arteries, reducing blood flow to the kidneys.
- Main causes
- Atherosclerosis (about 90%, older adults) and fibromuscular dysplasia (younger women).
- Clues
- High blood pressure that starts suddenly, is severe or resists 3 or more medicines; kidney function falling after starting ACE inhibitors or ARBs; sudden fluid on the lungs.
- Diagnosis
- Duplex ultrasound, CT or MR angiography, and catheter angiography.
- Treatment
- Blood pressure medicines, statins, antiplatelets, smoking cessation; angioplasty for fibromuscular dysplasia and selected cases.
When to get help
Call 911 or go to the ER
- Sudden severe breathlessness, especially lying flat, with very high blood pressure (possible flash pulmonary edema)
- Blood pressure of 180/120 mmHg or higher with chest pain, severe headache, confusion, vision changes or weakness
See a doctor within a day or two
- Blood pressure that suddenly becomes much harder to control
- A sharp rise in creatinine (falling kidney function) after starting an ACE inhibitor or ARB
- Very little urine output with swelling
Book a routine appointment
- High blood pressure starting before age 30, especially in women, or after age 55
- High blood pressure needing 3 or more medicines
- A whooshing sound (bruit) heard over the abdomen at a checkup
- Unexplained shrinking of one kidney on a scan
How renal artery stenosis raises blood pressure
When blood flow to a kidney falls, the kidney senses low pressure and releases renin. This activates the renin-angiotensin-aldosterone system, which constricts blood vessels and causes salt and water retention, raising blood pressure. Over time, reduced blood flow can shrink the kidney and reduce its function (ischemic nephropathy).
Causes
| Cause | Typical patient | Features |
|---|---|---|
| Atherosclerosis | Adults over 55, smokers, people with diabetes, high cholesterol, coronary or peripheral artery disease | Narrowing at the start of the renal artery, often progressive |
| Fibromuscular dysplasia (FMD) | Women aged 15 to 50 | Abnormal growth in the artery wall causing a "string of beads" pattern, also can affect neck arteries |
| Other (rare) | Vasculitis (such as Takayasu arteritis), aortic dissection, external compression, radiation |
Atherosclerosis affecting the renal arteries usually comes with atherosclerosis elsewhere, so heart attack and stroke risks are high.
Symptoms
Renal artery stenosis itself often causes no symptoms. Clues include:
- High blood pressure that: - starts suddenly or worsens after being well controlled - begins before age 30 or after age 55 - is resistant to 3 or more medicines, including a diuretic - is severe (malignant hypertension)
- Declining kidney function, especially a rise in creatinine of more than 30% after starting an ACE inhibitor or ARB
- Sudden episodes of fluid on the lungs (flash pulmonary edema) without another explanation
- Unexplained difference in kidney size of more than 1.5 cm on imaging
- An abdominal bruit, a whooshing sound heard with a stethoscope
- Low potassium from excess aldosterone
Fibromuscular dysplasia can also cause headaches, pulsatile ringing in the ears (pulsatile tinnitus), or neck pain if neck arteries are involved.
Diagnosis
- Blood and urine tests: creatinine, eGFR, potassium and urine protein.
- Duplex ultrasound of the renal arteries: noninvasive, measures blood flow speed, but depends on operator skill and body habitus.
- CT angiography: detailed images, needs contrast dye, caution with reduced kidney function.
- MR angiography: an alternative, with gadolinium contrast cautions in advanced kidney disease.
- Catheter angiography: the gold standard, often done when treatment with angioplasty is planned.
Treatment
Medical therapy
For most people with atherosclerotic stenosis, medical treatment is the mainstay:
- Blood pressure control with ACE inhibitors or ARBs (with careful monitoring of kidney function), calcium channel blockers, diuretics and others
- High-intensity statins
- Antiplatelet therapy such as aspirin
- Smoking cessation
- Diabetes control
Angioplasty and stenting
Large trials (such as CORAL and ASTRAL) found that stenting atherosclerotic renal artery stenosis did not improve kidney or heart outcomes compared with good medical therapy for most patients. Revascularization is now reserved for selected situations:
- recurrent flash pulmonary edema
- rapidly declining kidney function
- resistant hypertension despite optimal medicines
- severe stenosis in both arteries or in a single working kidney
Fibromuscular dysplasia
Balloon angioplasty without a stent often cures or greatly improves blood pressure in FMD, especially in younger patients, and is the preferred treatment when blood pressure is difficult to control. People with FMD should also have imaging of other arteries, since FMD can affect neck and brain arteries.
Surgery
Bypass surgery is rarely needed today, mainly for complex anatomy or when angioplasty fails.
Complications
- Chronic kidney disease and kidney failure
- Acute kidney injury, sometimes triggered by blood pressure medicines or dehydration
- Heart failure and flash pulmonary edema
- Heart attack and stroke
- Damage from long-standing high blood pressure to the eyes, brain and heart
Outlook
Atherosclerotic renal artery stenosis is a marker of widespread vascular disease, so controlling all cardiovascular risk factors is essential. With good medical therapy, many people maintain stable kidney function. Fibromuscular dysplasia has a good outlook, and angioplasty often improves blood pressure significantly.
Frequently asked questions
What are the symptoms of renal artery stenosis?
It often has no symptoms. Clues include high blood pressure that starts suddenly, is severe or does not respond to several medicines, falling kidney function after starting ACE inhibitors or ARBs, sudden fluid on the lungs, and one kidney being smaller than the other.
What causes renal artery stenosis?
About 90% of cases are caused by atherosclerosis, the buildup of fatty plaque, mainly in older adults with vascular risk factors. Most of the rest are caused by fibromuscular dysplasia, which typically affects younger women.
How is renal artery stenosis treated?
Most people are treated with blood pressure medicines, statins, antiplatelets and stopping smoking. Angioplasty, sometimes with a stent, is used for fibromuscular dysplasia and selected severe atherosclerotic cases, such as recurrent flash pulmonary edema.
Is renal artery stenosis serious?
It can be. It may cause hard-to-control high blood pressure, kidney damage and heart failure, and it often signals atherosclerosis elsewhere, raising heart attack and stroke risk. With good treatment, many people remain stable.
Can renal artery stenosis be reversed?
Narrowing from fibromuscular dysplasia can often be corrected with angioplasty. Atherosclerotic narrowing does not reverse, but medicines and lifestyle changes can slow progression and protect the kidneys and heart.
Sources
This guide was written from current patient and clinical guidance, including:
- American Heart Association/American College of Cardiology: Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults (secondary hypertension)
- NIDDK: Renal Artery Stenosis
- Society for Vascular Surgery: Renal artery disease
- CORAL trial (New England Journal of Medicine): Stenting and medical therapy for atherosclerotic renal-artery stenosis
- Fibromuscular Dysplasia Society of America: FMD overview
- MedlinePlus: Renal artery stenosis