Hypertension is an elevated blood pressure leading to end-organ damage, or a sus-tained diastolic pressure >90 mm Hg and/or systolic pressure >140 mm Hg.
Hypertension is very common, affecting 25% of the U.S. population. African Ameri-cans tend to be more seriously affected than Caucasians, and the risk increases with age. Approximately 95% of cases of hypertension are idiopathic (essential); the remainder are due to secondary hypertension related to renal disease, pheochromo-cytoma, or other disease processes.
Mild to moderate elevations in blood pressure cause end-organ damage by damag-ing arterioles with hyaline arteriolosclerosis. Late manifestations of hypertension include concentric left ventricular hypertrophy; congestive heart failure; accelerated atherosclerosis; myocardial infarction; aneurysm formation, rupture, and dissection; intracerebral hemorrhage; and chronic renal failure.
Malignant (accelerated) hypertension accounts for 5% of the cases and is charac-terized by markedly elevated pressures (e.g., systolic pressure >180 mm Hg and/or diastolic >120 mm Hg), which can rapidly cause end-organ damage. Funduscopic examination may demonstrate retinal hemorrhages, exudates, and papilledema. Malignant hypertension is a medical emergency; if untreated, most patients will die within 2 years from renal failure, intracerebral hemorrhage, or chronic heart failure.