Heart Attack

The heart is a remarkably effective muscle. Consider that if your heart beats 80 times a minute, in a single year it will pump blood through your body approximately 42 million times. It also pumps blood through itself. Like any muscle, your heart must also receive a supply of blood in order to work properly.

To get an idea of how hard your heart works, try clenching and unclenching your fist and see how long you can keep it up. You'll quickly find that your hand and arm soon begin to ache. That ache signals that the muscles are overworked. Yet your heart keeps up that pace 24 hours a day, every day, year after year. So it's vitally important to keep a supply of fresh oxygenated blood coming to the heart through open, unclogged blood vessels. The blood vessels that supply your heart with blood are called coronary arteries.

A heart attack occurs when a portion of the heart muscle dies from lack of oxygen. Usually a problem in the coronary arteries is the cause. These arteries are narrow, and their pathway in the heart follows many twists and turns. For a variety of reasons, they tend to become blocked. When the supply of oxygenated blood they deliver is cut off or reduced, you feel pain, just as you did in your hand and arm. When the pain comes from your heart, it's called angina. You can have angina without having a full-blown heart attack, but angina is a danger signal that can mean serious heart disease.

When your arm got sore from squeezing your fist, you probably stopped and gave it a rest. Unfortunately, your heart can't stop for very long without death as the result. So to try to rest, it starts beating with less force, which results in less blood being circulated throughout the body. This causes some of the symptoms of what is commonly called a heart attack: clammy skin, pallor, and profuse perspiration. Along with the pain from the heart attack, there is general weakness as blood flow to the brain decreases. The person suffering the heart attack may feel dizzy or even lose consciousness. If coronary artery blockage is severe enough, the heart stops beating altogether, and, within a few minutes, death occurs.

Heart attacks can vary greatly in severity. The first attack may be mild, or severe enough to be disabling, or even fatal. Some people never experience a subsequent attack, while others experience several before succumbing to a fatal attack. Having a heart attack does not necessarily mean that you may die any minute of heart disease, but it is a strong signal that help is needed to reduce this possibility. So one of the major areas of cardiac research has been the reduction and prevention of coronary artery disease. As a result, we now have dozens of drugs to prevent and reduce the devastating effects of cardiovascular illnesses.

What Is a Heart?

The subject of song and verse, the heart was believed by the ancients to be the seat of the soul and the emotions. Even today we send "heart-shaped" cards (which aren't really shaped anything like hearts) on Valentine's Day and refer to broken-hearted lovers, but modern science tells us that hearts are about as romantic as your car's oil pump. In fact, the heart is a pump -- a lumpy mass of muscle about the size of your fist that forces blood first through the lungs to pick up oxygen and then through the body to deliver that oxygen to the body's cells. That's a more mundane job than housing the soul, but vital nonetheless.

The rest of your circulatory system isn't much more difficult to understand than the heart. The arteries and veins are essentially tubing carrying the blood where it's needed around the body. But on closer inspection they turn out to be more than simple hoses.

Veins, for instance, have a series of valves that prevent blood from flowing backward as it returns to the heart. Arteries are really a combination of tubing and pump. The walls of the arteries are made up of layers of muscle that expand with every heartbeat and then rebound between heartbeats, giving the circulation an added boost.

The coronary arteries supply blood directly to the muscle tissue that makes up the heart. Like every other part of the body, the heart needs oxygen, and the coronary arteries' sole purpose is to supply it with oxygen-rich blood. They branch off from the aorta (the main artery that emerges from the heart) and snake along the surface of the heart itself .