Malignant hypertension and hypertensive emergencies.

Hypertensive emergencies and urgencies are important causes of morbidity and mortality. Malignant hypertension is a hypertensive urgency characterized by grade III/IV retinopathy and widespread endothelial damage. Control of BP is essential in the treatment of these disorders. The effects of hypertension on target organ function need to be balanced against the risks of excessive BP lowering. In hypertensive emergencies, BP should be lowered within minutes with parenteral agents to prevent critical end-organ damage. In hypertensive urgencies, BP can be lowered more slowly over several hours, often with oral agents, to avoid a detrimental fall in BP. The absolute indications for treatment and the optimal therapy depend on the underlying condition.