cardiovascular disorders
Hypertensive Emergencies
Introduction
A hypertensive emergency is severe hypertension (often defined as systolic blood pressure (BP) ≥ 180 mm Hg and/or diastolic blood pressure ≥ 120 mm Hg) with signs of damage to target organs (primarily the brain, cardiovascular system, and kidneys). Diagnosis is by BP measurement, ECG, urinalysis, and serum electrolyte and creatinine measurements. Treatment is immediate BP reduction with IV antihypertensives. (See also Hypertension .) Signs of target-organ damage include Hypertensive encephalopathy Hypertensive Retinopathy None Preeclampsia and Eclampsia None Acute Heart Failure (HF) with Overview of Coronary Artery Disease None Acute Aortic Dissection None Chronic Kidney Disease None Damage is rapidly progressive and sometimes fatal. Hypertensive encephalopathymay involve a failure of cerebral autoregulation of blood flow. Normally, as blood pressure increases, cerebral vessels constrict to maintain constant cerebral perfusion. Above a mean arterial pressure (MAP) of about 160 mm Hg (lower for people who are normotensive whose BP suddenly increases), the cerebral vessels begin to dilate rather than remain constricted. As a result, the very high BP is transmitted directly to the capillary bed with transudation and exudation of plasma into the brain, causing cerebral edema, including papilledema. Although many patients with Overview of Stroke and 