Contents
Introduction
Malignant hypertension (aka – hypertensive crisis) is a very high blood pressure that typically comes on suddenly and quickly. It is defined as systolic blood pressure of >180 mmHg and / or diastolic blood pressure of >120 mmHg PLUS signs of target organ damage.
- e.g. Papilloedema or retinal haemorrhages OR new onset confusion, chest pain, shortness of breath, heart failure or acute kidney injury
- Asymptomatic hypertension alone does not constitute malignant hypertension
- From my experience – this is the source of many unnecessary referrals to the emergency department from primary care
- Typically, for target organ damage to occur, blood pressure is above 220 / 140 mmHg
It typically develops in people with long-standing uncontrolled hypertension, although the incidence is rare (<1% of hypertensive patients). It is more common in people of African origin, and in men, and typically presents in patient sin their 40s and 50s.
True malignant hypertension is a medical emergency.
- If a hypertensive crisis presents in pregnancy, consider eclampsia, which is important as the treatment is different
Malignant hypertension carries a significant mortality and morbidity. In cases where renal failure develops, survival at 12 months is about 80%.
Aetiology
- Affects ~1% of people with hypertension
- Children and adults
- More common in young adults
- M>F
- Especially African American men
- Most common the result of essential hypertension, but can also result from other secondary causes of hypertension
- Common in those with collagen vascular disorders: SLE, systemic sclerosis and periarteritis nodosa
- Patients with kidney failure or renal hypertension as a result of renal artery stenosis are at an increased risk of malignant hypertension
- Associated with toxaemia of pregnancy
Pathophysiology
- Humoral vasoconstrictors initiate an abrupt increase in systemic vascular resistance.
- Endothelial injury, fibrinoid necrosis of arterioles and deposition of platelets and fibrin result.
- There is a breakdown of normal autoregulatory function. Resulting ischemia prompts release of further vasoactive substances, prompting re-initiation of the cycle.
- Homeostatic failure begins, leading to loss of cerebral and local autoregulation, organ system dysfunction and MI.
- The effects of malignant hypertension can include:
- Renal failure
- Pulmonary Oedema
- Encephelopathy
- Cerebrovascular haemorrhage
- Papilloedema
Symptoms and Signs
- Change in GCS/ mental status: anxiety, confusion, decreased alertness, decreased ability to concentrate, fatigue, restlessness, sleepiness, stupor, lethargy
- Sign of increased ICP:
- Headache
- N&V
- Subarachnoid/ cerebral haemorrhage
- Seizure
- Blurred vision
- Chest pain – crushing/ pressure
- Cough
- Reduced U/O
- SOB
- Paraesthesias and weakness of limbs/face
Examination
- Extremely high BP
- Lower limb and foot oedema
- Abnormal heart sounds
- Pulmonary oedema
- Abnormal reflexes
- Changes in sensation
- Changes in power/tone
Ophthalmoscopy
The retina is the only place that arteries can be directly visualised, and therefore gives a snapshot of blood vessel pathology.
- Bleeding of the retina: flame-shaped haemorrhages
- Narrowing of retinal blood vessels
- Papilloedema (this must be present for the diagnosis of malignant hypertension to be made)
- Hard exudates
- Cotton wool spots
Investigations
- ABG
- Urea
- Creatinine
- Urinalysis and urine dip
- For proteinuria
- In severe cases – may also show red cell casts
- CXR
- Congestion in the lung
- Cardiomegaly
- Brain CT – for evidence of raised ICP
- ECG
- U&E, renin and aldosterone levels
- Cardiac enzymes (markers of heart damage)
- Pathological hallmark = fibrinoid necrosis
Management
Malignant hypertension is a medical emergency! Patients should be admitted to hospital until their blood pressure is under control.
In a hypertensive emergency, the blood pressure should be lowered slowly over a period of days. This is because cerebral autoregulation is poor, so sudden drops in blood pressure increase the risk of stroke.
- Insert an arterial line
- OR measure blood pressure at least every 5 minutes via a non-invasive method
- Aim to reduce blood pressure by a maximum of 25% in the first 2 hours
- Use an IV medication with a short duration of action
- This means that any over-lowering of BP is easy to correct – as the drug wears off quickly. Examples include:
- Hydralazine 1mg IV bolus – repeat every minute up to a maximum of 5mg
- Metoprolol 1mg IV bolus – also repeat every minute up to a maximum of 5mg
- Then, set up an IV infusion. Options include:
- Sodium nitroprusside 0.3 mcg/kg/minute – titrate to effect to MAX 10mcg/kg/minute
- Glyceryl trinitrate 10 mcg/minute – titrate to effect to MAX 100mcg/minute
- Esmolol infusion
- Labetolol infusion
- Treat end-organ effects
- Consider diuretics for pulmonary oedema if necessary
- Consider for dialysis if indicated
- Admit the patient to the ward
- Over the following hours and days, the patient is typically weaned to an oral regimen of anti-hypertensives
- Typically atenolol or long-acting Ca2+ blockers are used PO
- The former use of oral nifedipine, a calcium channel blocker, has been strongly discouraged because it has been noted to lead to serious and fatal hypotensive problems.
Prognosis
Many body systems are at risk of serious damage from an extreme rise in blood pressure. Without treatment, 90% die in 1 year, but if treated there is a 70% 5 year survival rate.
Possible complications include:
- Brain damage (stroke, seizures)
- MI, angina, heart rhythm disturbances
- AKF
- Blindness
- Pulmonary oedema
Blood vessels of the kidney are particularly susceptible, and kidney failure may develop. This can be permanent and patients may become reliant upon dialysis.
However, if treated immediately, malignant hypertension can often be controlled without causing permanent problems. Patients known to suffer from hypertension are advised to monitor it regularly and take their medications regularly to avoid this medical emergency.
References
- eTG – Urgent control of elevated blood pressure
- Murtagh’s General Practice. 6th Ed. (2015) John Murtagh, Jill Rosenblatt
- Oxford Handbook of General Practice. 3rd Ed. (2010) Simon, C., Everitt, H., van Drop, F.
- Beers, MH., Porter RS., Jones, TV., Kaplan JL., Berkwits, M. The Merck Manual of Diagnosis and Therapy