Malignant Hypertension

What malignant hypertension is

Normal blood vessels can cope with short spikes in blood pressure. When pressure stays extremely high, the smallest arteries are injured. Their walls swell and thicken, red blood cells are sheared apart as they squeeze through, and organs downstream are starved of blood. This process, called fibrinoid necrosis and thrombotic microangiopathy, causes a vicious cycle: damaged kidneys release renin, which constricts arteries and raises blood pressure further.

The term "malignant" comes from the days before treatment, when most people died within a year, as with an aggressive cancer. Today it is classed as a type of hypertensive emergency, defined by severe hypertension with signs of retinal damage: bleeding, cotton-wool spots and swelling of the optic disc (papilledema).

Hypertensive emergency vs hypertensive urgency

Symptoms

• Severe headache, often at the back of the head and worse in the morning
• Blurred vision or vision loss
• Chest pain or tightness
• Shortness of breath, especially lying flat, from fluid in the lungs
• Nausea and vomiting
• Confusion, drowsiness, seizures (signs of hypertensive encephalopathy)
• Weakness or numbness on one side, or difficulty speaking (possible stroke)
• Reduced urine output or blood in the urine
• Nosebleeds and fatigue

Causes

Most people who develop malignant hypertension already have high blood pressure that has been untreated or poorly controlled. Common triggers and underlying causes:

• Untreated or uncontrolled primary hypertension, or suddenly stopping medicines such as clonidine or beta-blockers
• Kidney disease: chronic kidney disease, glomerulonephritis, renal artery stenosis
• Scleroderma renal crisis, a complication of systemic sclerosis
• Hormone conditions: pheochromocytoma, primary hyperaldosteronism, Cushing syndrome
• Drugs: cocaine, amphetamines, MAO inhibitors combined with tyramine-rich foods, high-dose decongestants, some cancer drugs (VEGF inhibitors), steroids and NSAIDs in susceptible people
• Pregnancy: severe preeclampsia and eclampsia
• Spinal cord injury (autonomic dysreflexia)

Who is at higher risk

Malignant hypertension is more common in men, younger adults with untreated hypertension, Black people, smokers and people with limited access to regular care.

Diagnosis

Doctors move quickly to confirm the diagnosis and find which organs are affected:

• Repeated blood pressure measurements, sometimes via an arterial line
• Eye exam (fundoscopy) for retinal bleeding, cotton-wool spots and papilledema, the hallmark of malignant hypertension; see hypertensive retinopathy
• Blood tests: kidney function, electrolytes, blood count and smear for fragmented red cells, platelets, LDH, troponin
• Urine tests for protein and blood
• ECG and chest X-ray for heart strain and lung fluid
• CT or MRI of the brain if there are neurological symptoms
• CT angiogram if aortic dissection is suspected
• Later, tests for secondary causes such as renal artery stenosis or hormone disorders

Treatment

In the hospital

Treatment happens in an emergency department or intensive care unit with continuous monitoring. Intravenous medicines such as nicardipine, clevidipine, labetalol, esmolol or nitroprusside allow precise control.

The aim is to lower blood pressure gradually. Bringing it down too fast can starve the brain, heart and kidneys of blood, because they have adapted to the high pressure. A typical plan:

1. Lower blood pressure by no more than about 25% in the first hour.
2. Then toward 160/100 to 110 mm Hg over the next 2 to 6 hours.
3. Then toward normal over the next 24 to 48 hours.

Exceptions where pressure is lowered faster include aortic dissection, severe preeclampsia or eclampsia, and pheochromocytoma crisis.

After the emergency

• Switching to oral medicines, often several combined
• Investigating and treating secondary causes
• Dialysis, temporary or long term, if kidney damage is severe
• Frequent follow-up, home blood pressure monitoring and support to take medicines every day

Complications

• Acute kidney injury and chronic kidney failure
• Stroke, brain bleeding and hypertensive encephalopathy
• Heart attack, heart failure and fluid on the lungs
• Aortic dissection
• Permanent vision loss
• Thrombotic microangiopathy, with destruction of red blood cells and low platelets

Outlook

Untreated, malignant hypertension historically killed most people within a year. With modern treatment, most survive, and the majority are alive 5 years later. The long-term outlook depends mostly on kidney function at diagnosis and on how well blood pressure is controlled afterwards. Some people who need dialysis recover enough kidney function to stop it in the following months.

Preventing a hypertensive crisis

• Check your blood pressure regularly, and treat high readings early.
• Take blood pressure medicines every day; do not stop them suddenly.
• Avoid cocaine, amphetamines and excess decongestants.
• Ask your pharmacist before taking new over-the-counter medicines.
• Keep follow-up appointments, especially if you have kidney disease or scleroderma.

Frequently asked questions

What blood pressure is considered malignant hypertension?

There is no single number. It is usually seen with readings of 180/120 mm Hg or higher, often with a diastolic reading above 120 to 130. What defines it is organ damage, especially bleeding and swelling at the back of the eye, rather than the reading alone.

Is malignant hypertension the same as a hypertensive crisis?

Hypertensive crisis is the umbrella term for blood pressure at or above 180/120 mm Hg. It is split into urgency (no organ damage) and emergency (organ damage). Malignant hypertension is a type of hypertensive emergency defined by damage to the retina.

Why don't doctors lower blood pressure quickly?

After months or years of high pressure, the brain, heart and kidneys adjust to need a higher pressure to get enough blood flow. Dropping it too fast can cause a stroke, heart attack or kidney injury. That is why the first goal is a reduction of no more than about 25% in the first hour.

Can malignant hypertension be cured?

The emergency can be treated, and blood pressure can usually be controlled long term with medicines. If a secondary cause is found and fixed, such as renal artery stenosis or a pheochromocytoma, blood pressure may improve greatly. Some organ damage, especially to the kidneys, may be permanent.

Should I go to the ER for blood pressure of 180/120?

If you have symptoms such as chest pain, shortness of breath, severe headache, vision changes, confusion or weakness, call 911 or your local emergency number. If you feel well, rest for 5 minutes and recheck. If it is still that high, contact your doctor the same day.