Directly or indirectly, high blood pressure accounts for nearly a million deaths a year. Uncontrolled, high blood pressure increases the odds that you'll have a heart attack, stroke, kidney failure or loss of vision. High blood pressure happens when your blood moves through your arteries at a higher pressure than normal. The heart is actually straining to pump blood through the arteries. Hardened, narrowed arteries may not be able to carry the amount of blood the body's organs need.
Blood clots can form or lodge in a narrowed artery.
The heart can become enlarged. More than half of all older adults have high blood pressure. About 50 percent of all people who have it don't know it. Worse yet, many people who know their blood pressure is dangerously high are doing nothing to try to control it. And for 90 percent of those affected, there is no known cause.