The human heart beats approximately once a second. During the day, it pumps about 2,000 gallons of blood through the circulatory system. Like any muscle, the heart needs a steady supply of blood, or the tissue will be damaged and begin to die. Without blood, heart cells are injured, causing pain or pressure.

A heart attack occurs when one or more of the tiny arteries supplying your heart with oxygen-rich blood become blocked. These arteries are called coronary arteries because they encircle the top portion of your heart like a crown. Blockages are usually due to a blood clot that forms suddenly where a coronary artery has narrowed over the years from a buildup of cholesterol and other deposits.

This buildup of cholesterol and other deposits - collectively known as plaques - in arteries throughout the body is called atherosclerosis. When the coronary arteries narrow due to atherosclerosis, the condition is known as coronary artery disease.

Coronary artery disease is a major underlying cause of heart attacks. Some of the factors that increase your risk of narrowed coronary arteries, and thus, a heart attack, include a family history of heart disease, a high level of low-density lipoprotein cholesterol, the so-called "bad" cholesterol, high blood pressure, smoking, obesity and physical inactivity.

Rarely, a heart attack can occur when a blood clot from inside a diseased heart breaks loose and lodges in a healthy or narrowed coronary artery. Another uncommon cause of a heart attack is a spasm of a coronary artery that shuts down blood flow to part of the heart muscle. Drugs such as cocaine can cause such a life-threatening spasm.

A heart attack is not a static one-time event. It's a dynamic process that typically evolves over several hours. With each passing minute, more heart tissue is deprived of blood and deteriorates or dies. However, if blood flow can be restored in time, damage to the heart can be limited or prevented.

During a heart attack, many people waste precious minutes because they don't recognize the important signs and symptoms, or they deny them. Many people also delay calling for help because they're afraid to risk the embarrassment of a false alarm. However, one of the most important things you can do to survive a heart attack is to recognize what's happening and to take immediate action. Of the people who die of heart attacks, most die within the first hour after the onset of signs and symptoms. Don't waste time, minutes matter.

The warning signs and symptoms of a heart attack include:

• Pressure, fullness or a squeezing pain in the center of your chest that lasts for more than a few minutes
• Pain extending beyond your chest to your shoulder, arm, back, or even to your teeth and jaw
• Increasing episodes of chest pain
• Prolonged pain in the upper abdomen
• Shortness of breath
• Sweating
• Impending sense of doom
• Lightheadedness
• Fainting
• Nausea and vomiting

When a heart attack occurs, it’s critical to recognize the signs and respond immediately. Time is critical. When a coronary artery is blocked, the heart muscle doesn’t die instantly. But damage increases the longer an artery stays blocked. Delay may increase the damage to the heart and reduce the chance of survival. It also lessens the chance of preserving heart muscle. This increases the risk of disability.

Anyone who has the warning signs of a heart attack should be rushed to the nearest hospital with 24-hour emergency cardiovascular care. People who pass out before reaching the emergency room may receive cardiopulmonary resuscitation. Most communities have an emergency cardiovascular care system that can respond quickly. This prompt care dramatically reduces heart damage. In fact, 88 percent of heart attack survivors under age 65 can return to their usual work. Prompt care isn’t the only reason so many heart attack survivors recover so quickly, but it’s an important one.

The goal of emergency treatment of a heart attack is to restore blood flow and save heart tissue. The purpose of subsequent treatment is to promote healing of your heart and prevent another heart attack. Cardiac rehabilitation programs begin while you're in the hospital and, depending on the severity of your attack, continue for weeks to months after you return home. Cardiac rehabilitation programs generally focus on three main areas — medications, lifestyle changes and emotional issues.