What is the healthy heart? It's the heart that most people are born with—a powerful, four-chambered miracle of efficiency about the size of a clenched fist.
A healthy adult heart pumps five quarts of blood through 60,000 miles of flexible, smooth tubing every minute. Arteries carry blood away from the heart, bringing oxygen and nutrients to every part of the body, including the heart muscle. On the return trip through the veins, the blood carries very little oxygen.
Smokers' risk for heart disease is four times greater than the risk for nonsmokers.
For the healthy heart, "tired blood" flowing into the right side of the heart is an easy problem to solve. The heart pumps the blood into the lungs, where waste such as carbon dioxide is discharged. After loading up with oxygen, the blood flows back to the left side of the heart, which—once again—pumps it to every tissue in the body.
One of the heart's marvels is its electrical system, a group of cells that generate the electrical impulses that make the heart contract. Between contractions, the heart relaxes, enabling it to refill with blood. Though you hear only one beat, a contracting heart beats twice, once in the atria, or upper chambers, and once in the ventricles, or lower chambers. This squeeze-relax process occurs an average of 70 times a minute, 100,800 times a day, and nearly 37 million times a year.
Healthy hearts can also be defined by what they aren't. They aren't pooped. A weakened heart may not contract and relax easily. Fluids will back up in the veins and congest the legs, lungs, and other parts of the body.
Nor are healthy hearts dependent on off-again, on-again electrical systems, a challenge for aging heart muscles. Healthy hearts don't need battery-driven pacemakers to keep them beating regularly.
Healthy hearts aren't fed by arteries that are narrowed by plaque. Their owners take good care of them: They don't sit too much, drink too much alcohol, smoke, weigh too much or consume foods that have too much saturated fat.