Accelerated Hypertension

Accelerated hypertension may be seen in association with renal disease or may occur as a discrete entity and will occur in approximately 1% of patients with essential hypertension. Average age at presentation is 40 years. Men are more commonly affected than women.

Risk factors

• Cigarette smoking
• Black ethnic origin
• Secondary hypertension sufferers

Accelerated hypertension may occur due to raised renin levels e.g. those found in association with:²

• Unilateral renovascular hypertension
• Renin-secreting neoplasms
• Trauma to the kidneys
• Renal vasculitis e.g. scleroderma, polyarteritis and systemic lupus erythematosus
• Pheochromocytoma
• Cocaine abuse
• Clonidine withdrawal
• Sodium-volume overload and low renin levels e.g. acute glomerulonephritis, primary aldosteronism
• Pre-eclampsia/eclampsia

This may be asymptomatic or may present with any of the many symptoms and/or signs of end organ damage:

• Headache
• Fits
• Nausea and vomiting
• Visual disturbance
• Chest pain
• Neurological deficit e.g. cerebrovascular event (CVE)
• Bleeding due to disseminated intravascular coagulopathy (DIC)
• Microangiopathic haemolytic anaemia

The investigation of any patient thought to have accelerated hypertension should be undertaken urgently and by doctors with expertise in this field. Investigations should include:¹

• Full history - including:
  • Past medical history
  • Full systems review
  • Drug history including over the counter, herbal remedies and recreational drugs
• Full examination - including:
  • Blood pressure measurements lying, standing and in both arms
  • Fundoscopy
  • Neurological examination
• ± Ambulatory blood pressure monitoring
• Urine dip testing for protein and blood
• U&Es
• Blood sugar measurement
• Fasting blood lipids
• ECG
• ±CT/MRI scan of head or kidneys
• ±Plasma renin activity
• ±Plasma aldosterone level
• ±Catecholamine levels
• FBC ± clotting screen
• ±Creatinine clearance
• ±Auto-antibody levels e.g. anti-nuclear factor

General measures

The aim is to reduce the blood pressure over 24-48 hours. This may be possible as an outpatient with oral medication by adding treatments and increasing doses stepwise. See the Management of Hypertension record.

However, patients may be admitted to hospital. They usually have altered blood pressure autoregulation and if the blood pressure is reduced too fast, there may be organ hypoperfusion.

• Initially try to reduce the mean arterial pressure by approximately 25% over the first 24-48 hours.
• An arterial line is helpful for continuous blood pressure monitoring.
• There may be severe sodium and volume depletion; volume expansion with isotonic sodium chloride solution may be required.

Pharmacological

Nitroprusside is the most commonly used intravenous (IV) drug:³

• Acts by causing relaxation of vascular smooth muscle, resulting in vasodilation and inotropy.
• Adult dose initially 0.3–1.5 micrograms/kg/minute, then increased in steps of 500 nanograms/kg/minute every 5 minutes within range 0.5–8 micrograms/kg/minute (use lower doses if on other antihypertensives); stop if response unsatisfactory at maximum dose after 10 minutes.⁴

Labetalol is another common alternative:

• Close patient monitoring is necessary (hypotension and heart block can occur).
• Start oral antihypertensive therapy as soon as possible.
• Adult dose 50 mg over at least 1 minute, repeated after 5 minutes if required. Do not exceed 200 mg per dose.⁴
• Alternatively a continuous IV infusion at 2 mg/min can be started, with subsequent adjustment.

Phentolamine is the drug of choice for a pheochromocytoma crisis:

• It blocks circulating adrenaline and noradrenaline action, reducing hypertension that results from catecholamine effects on the alpha-receptors.
• May be useful in withdrawal from alpha agonists or the interaction of monoamine oxidase inhibitors with tyramine-containing foods, but it is less titratable than nitroprusside.
• Adult dose 2-5 IV repeated as necessary.⁵

Also available parenterally are diltiazem, verapamil and enalapril. Hydralazine is reserved for use in pregnant patients.

Without treatment accelerated hypertension may result in death within a year in over 90% of patients as a result of end organ damage e.g. myocardial infarction (MI), CVE or renal failure. The prognosis has improved dramatically over the last few decades and with optimal treatment the 5 year survival rate is > 80%.