Hypertensive crisis is severe hypertension with acute impairment of an organ system (e.g., central nervous system [CNS], cardiovascular, renal). In these conditions, the blood pressure (BP) should be lowered aggressively over minutes to hours.

This hypertensive emergency is defined as a critical elevation in blood pressure in which diastolic pressure exceeds 120 mm Hg. The hypertensive crisis occurs most often in patients with a known history of pre-existing hypertension. A hypertensive crisis also may be superimposed on other diseases that cause hypertension, particularly renovascular disease, renal parenchymal disease, and pheochromocytoma.

Hypertensive crisis can occur at any age. It can affect neonates with congenital renal artery hypoplasia, children with acute glomerulonephritis, young pregnant women with eclampsia, or elderly people with atherosclerotic renal artery stenosis.

Hypertension affects 25-30% of the population. Of these individuals, 10% have severe hypertension (diastolic BP [DBP] >110 mm Hg) and approximately 1-2% develop a hypertensive emergency with end-organ damage.

Hypertensive emergencies generally require a reduction in blood pressure within a few hours, usually using intravenous medications given in an intensive care unit.