Malignant hypertension is very high blood pressure that comes on suddenly and quickly. The diastolic BP reading (normally <80mmHg) is often >130mmHg, and systolic is usually >200mmHg.
- Affects ~1% of people with hypertension
- Children and adults
- More common in young adults
- Especially African American men
- 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
- 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.
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:
- Subarachnoid/ cerebral haemorrhage
- Blurred vision
- Chest pain – crushing/ pressure
- Reduced U/O
- Paraesthesias and weakness of limbs/face
- Extremely high BP
- Lower limb and foot oedema
- Abnormal heart sounds
- Pulmonary oedema
- Abnormal reflexes
- Changes in sensation
- Changes in power/tone
- 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
- Congestion in the lung
- Brain CT
- U&E, renin and aldosterone levels
- Cardiac enzymes (markers of heart damage)
- Pathological hallmark = fibrinoid necrosis
Malignant hypertension is a medical emergency! Patients are 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.
- Chest pain requires lowering of BP. 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.
- IV sodium nitroprusside has an almost immediate antihypertensive effect in the acute emergency setting to get hypertension below dangerous levels.
- In less urgent cases, oral agents such as captopril, clonidine labetalol or prazosin can be used, though these have a delayed onset of action in comparison to IV sodium nitroprusside.
- Atenolol or long-acting Ca2+ blockers may then be used PO.
- Diuretics for pulmonary oedema if necessary.
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
- 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.