Hypertensive crisis: Emergency and urgency

Hypertension crisis is defined as new or progressive end-organ damage associated with high blood pressure and requires immediate blood pressure control over the course of minutes to hours. Hypertensive urgency, which is defined as a very high blood pressure in the absence of end-organ damage, is a misnomer, and does not require acute reduction of blood pressure; rather, acute aggressive reduction could be harmful. The pathophysiology of hypertensive emergency is not clear but it is proposed to involve a sudden rise in blood pressure that causes vascular myogenic response and endothelium damage, resulting in an increase in vasoactive hormones and vessel damage (fibrinoid necrosis and myointimal proliferation). This sets up a vicious cycle of increased peripheral vascular resistance and worsening of hypertension. Management of hypertension emergencies begins with careful assessment of blood pressure, end-organ damage (most of the time brain, heart, and kidney), identification of reversible insults, and institution of parenteral antihypertensives in most circumstances. The choice of antihypertensive and level of blood pressure reduction depend on the etiology and type of hypertensive organ damage.