DISEASEOF THE MONTH Malignant Hypertension and Hypertensive Emergencies

Hypertensive crisis refers to a syndrome characterized by severe BP elevation associated with imminent risks to the patient (1,2). It is a common clinical problem and accounts for 27.5% of all medical emergencies presenting to the emergency department (3). It is useful to distinguish between hypertensive emergencies (Table 1 ), in which BP should be lowered within minutes, and hypertensive urgencies (Table 2), in which BP can be lowered more slowly over several hours. The most important determinant for the urgency of treatment is detenioration of vital organ function secondary to the hypertension. The absolute level of BP itself is less important, because even modest, acute increases in BP may lead to critical end-organ damage in previously normotensive patients (e.g. , pre-eclampsia and acute glomerubonephritis) and in those with an accompanying medical condition (e.g. , aortic dissection or acute myocardial infarction). Malignant hypertension denotes the presence of KeithWagener grade IV retinal changes (papilbedema), whereas accelerated hypertension traditionally has been used to define hypertension accompanied by grade III retinopathy (hemorrhages, cotton wool spots, and hard exudates without papilledema). The two conditions share similar etiology, pathology, and prognosis, and unless stated otherwise, both conditions will be referred to as malignant hypertension in this review. Malignant hypertension may develop in patients with preexisting hypertension or in previously nonmotensive patients. The etiology of hypertension itself is less important in deciding the urgency of treatment, but it may have an influence on the choice of agents used. The development of potent antihypertensive agents and the widespread availability of dialysis have resulted in significant reductions in morbidity and mortality due to malignant hypertension. This review will discuss the pathophysiology, clinical presentation, treatment, and outcome of malignant hypertension and other hypertensive crises.