High blood pressure is called the silent killer because it seldom causes warning symptoms, so you can have it and not know it. One of the most common cardiovascular diseases, high blood pressure, also called hypertension, affects one in every four adult Americans. Fifty-four percent of people older than 60 have high blood pressure, and by the time they reach 70, two in three Americans have it. Blood pressure is the tension or force that is placed on the inside walls of arteries to keep blood flowing through the body. Blood doesn't flow in a steady stream, but moves through the circulatory system in spurts determined by your heart's beats. With each beat, about two ounces of freshly oxygenated blood are forced out of the left ventricle (the main pumping chamber) into the aorta and into the body's 60,000 miles of blood vessels. Your blood pressure is constantly changing, depending on how hard the heart is working. During exercise, for instance, the heart can pump up to three times as fast as during periods of rest. Between heartbeats, the heart muscle rests momentarily and gets ready for the next beat. Blood pressure is measured by two numbers, such as 110 over 70 or 110/70. The higher number, called the systolic pressure, is the highest pressure in your arteries when your heart contracts and exerts maximum force on the walls of blood vessels during a heartbeat. The lower number, called the diastolic pressure, is the lowest pressure in your arteries when your heart relaxes momentarily between beats and fills with blood. The longer high blood pressure goes undiagnosed and untreated, the worse the outlook, because the heart is forced to work harder than normal. Blood pressure is like a weight or load that the heart muscle must lift, and like any muscle, your heart gets larger with heavy lifting. Eventually, the muscle can no longer adapt to the excessive work load, and the heart's pumping efficiency decreases. If this occurs, the heart muscle may weaken and congestive heart failure may develop. By accelerating the development of atherosclerosis in your arteries as you age, high blood pressure increases the chances of a stroke or heart attack. And by putting increased pressure on your artery walls, high blood pressure also can predispose a person to an aneurysm, a weakened bulge in an artery. Because high blood pressure is a risk factor for so many forms of heart disease, it's important to get it
under control. Many studies have demonstrated a direct relationship between high blood pressure and stroke, heart disease and kidney failure. Compared with people whose high blood pressure is under control, those with uncontrolled high blood pressure are about three times more likely to have coronary artery disease, about six times more likely to have congestive heart failure and about seven times more likely to have a stroke.
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