Chapter

Hypertensive urgencies and emergencies

Gregory Y.H. Lip and D. Gareth Beevers

in Oxford Textbook of Medicine

Fifth edition

Published on behalf of Oxford University Press

ISBN: 9780199204854
Published online May 2012 | e-ISBN: 9780199570973 | DOI: http://dx.doi.org/10.1093/med/9780199204854.003.161705_update_001

Series: Oxford Textbooks

Hypertensive urgencies 				and emergencies

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Hypertensive urgencies and emergencies occur most commonly in patients with previous hypertension, especially if inadequately managed. About 40% of cases have an underlying cause, most commonly renovascular disease, primary renal diseases, phaeochromocytoma, and connective tissue disorders. Hypertensive emergencies occur when severely elevated or sudden marked increase in blood pressure is associated with acute end-organ damage.

The key pathophysiological process is intense peripheral vasoconstriction, resulting in a rapid rise in blood pressure and a vicious circle of events, including ischaemia of the brain and peripheral organs.

Hypertensive urgencies

Malignant-phase hypertension is a rare condition (1–3 per 100 000 per year, more common in blacks) characterized by very high blood pressure, with bilateral retinal haemorrhages and/or exudates or cotton wool spots, with or without papilloedema.

Presentation is typically with visual disturbance, with or without headaches. Urinalysis may demonstrate proteinuria and haematuria, even in the absence of primary renal disease. Some patients with mild renal impairment at first presentation may improve, or even regain normal renal function, but this is unlikely to occur in those with more severe renal impairment at presentation.

Patients with severe hypertension who are asymptomatic require controlled reduction in blood pressure with oral antihypertensive agents. Over-rapid blood pressure reduction may be hazardous, leading on occasion to ischaemic complications such as stroke, myocardial infarction, or blindness. The maximum initial fall in blood pressure should not exceed 25% of the presenting value, with the initial aim of treatment being to lower the diastolic pressure to about 100 to 105 mmHg over a period of 2 to 3 days. The first-line oral antihypertensive agent is either a short-acting calcium antagonist (such as nifedipine, 10–20 mg of the tablet formulation: sublingual or capsular preparations should never be used) or a β-blocker (such as atenolol, 25 mg initial dose).

Hypertensive emergencies

Patients who are symptomatic with acute life-threatening complications of severe hypertension, such as hypertensive encephalopathy, hypertensive left ventricular failure, or aortic dissection, require parenteral antihypertensive therapy to promptly reduce the blood pressure in a carefully controlled manner. Blood pressure should be reduced by 25% over several hours, depending on the clinical situation, usually with a target diastolic blood pressure of less than 100 to 110 mmHg. The first-line treatment for most hypertensive emergencies is either intravenous sodium nitroprusside or intravenous labetolol, with β-blockade essential in patients with aortic dissection.

Hypertensive emergencies and urgencies carry a poor short- and long-term prognosis unless adequately managed. Initial over-rapid reduction of blood pressure to a normal value is dangerous, but—in the long term—blood pressure should eventually be reduced to accepted blood pressure targets.

Chapter.  6546 words.  Illustrated.

Subjects: Cardiovascular Medicine

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