Hypertension
Hypertension, or high blood
pressure, is a common disorder that affects up to 20% of the adult population
in the United States. It is defined as a consistently elevated blood
pressure of at least 140/90 mm Hg. The first figure shows the pressure against the arterial walls during cardiac contraction (systole), and the second figure shows the pressure against the arterial walls during cardiac expansion (diastole). Most cases of high blood pressure involve primary (essential)
hypertension, with an unknown cause. In 5-10% of cases, the hypertension is caused by some other disease and is known as secondary hypertension.
About 50 million Americans are affected by hypertension; African Americans and Hispanic Americans are at especially high risk. Hypertension rarely causes symptoms, and 35% of patients are unaware they have the disease until they are diagnosed for some other problem. It is easily treated, but control depends on patient awareness and compliance with drug therapy. Uncontrolled hypertension can cause a fatal heart attack or stroke, as well as severe kidney damage or heart failure.