High blood pressure, also called hypertension, refers to blood pushing against the walls of the arteries with chronically elevated force. Blood pressure that rises above normal levels and remains high can lead to serious health problems including heart attack, heart failure, stroke and kidney failure as well as other health problems.
High blood pressure is defined as a reading above 140/90 mm Hg (millimeters of mercury). In blood pressure measurement the top number, known as the systolic pressure, represents the pressure within the arteries when the heart contracts, or “beats" while pumping blood. The second number, diastolic pressure, represents the pressure in the arteries when the heart relaxes between beats and fills with blood.
Normal blood pressure is defined as less than 120 over less than 80. A person whose blood pressure runs between 120-139 over 80-89 is said to have pre-hypertension, a classification that is used to further encourage taking preventive diet and lifestyle measures. Blood pressure changes repeatedly throughout the day; it is lowest during sleep and increases upon waking. It also goes up when a person is excited, nervous or active.
Hypertension is the most common risk factor for cardiovascular disease in the U.S., affecting one in three adults, according to the National Heart, Lung and Blood Institute (NHLBI). Untreated, hypertension can lead to arterial damage, which in turn can result in impaired blood flow to vital organs, potentially leading to heart attack, kidney failure, stroke, eye damage or aneurysm. Fortunately, once identified, hypertension often can be controlled to some degree with changes in diet and lifestyle.