Heart Disease Overview

Heart disease is a general term for any disorder of the heart and its ability to circulate blood throughout the body. According to the Centers for Disease Control and Prevention (CDC):

• Heart disease is the leading cause of death for American Indians and Alaska Natives, African Americans, Hispanics, and Caucasians.
• Heart disease is the second leading cause of death for Asians and Pacific Islanders (cancer is the leading cause of death).
• The age–adjusted death rates for diseases of the heart were 30% higher among African Americans than among whites.

In 2002:

• 696,947 people died of heart disease. This was 29% of all deaths (approximately half were women).
• 494,392 people died from coronary artery disease. This was 71% of all heart disease deaths.

How the heart works

The heart is a muscle that pumps blood throughout the body. The heart, blood vessels, and blood make up the body's cardiovascular system, which helps:

• Bring oxygen and nutrients to the body.
• Remove carbon dioxide and waste products from the body.

The right side of the heart pumps oxygen-poor blood to the lungs, where the blood picks up oxygen. The blood is then returned to the left side of the heart, which pumps the oxygen-rich blood to the body. Each side of the heart has two chambers. The upper chambers are called atria (singular: atrium). The lower chambers are called ventricles. Valves control the flow of blood between the atria and the ventricles.

A heartbeat is a single pulsation of the heart. First the atria contract, then the ventricles contract, and then the entire heart relaxes. The heart's electrical system controls the speed of a person's heartbeat.

Common types of heart disease

Heart disease is usually caused by atherosclerosis, which is a build up of fatty deposits (plaques) on the inner walls of the blood vessels. If left untreated, the blood vessels become narrow or even blocked, which interferes with the supply of blood throughout the body. Heart disease may also be caused by an infectious disease (such as rheumatic fever due to strep throat) or a congenital heart disease (such as heart obstruction defects present at birth).

Common types of heart disease include coronary artery disease, angina, heart attack, heart failure, and heart arrhythmias.

Coronary artery disease

Over time, the coronary arteries narrow and thicken, reducing or even stopping the supply of oxygen-rich blood to the heart muscle. If left untreated, coronary artery disease can lead to angina, heart attack, and heart failure.

Angina

• Stable angina
  Stable angina is the most common type of angina. It is a chronic condition that occurs during physical activity or emotional stress and stops with rest or medications.
• Unstable angina
  Unstable angina may occur during physical activity or while resting. It is more severe than stable angina and doesn't respond to medication. Unstable angina is a sign of an impending heart attack and requires emergency treatment.
• Variant angina
  Variant angina is a rare type of angina. It is a temporary spasm that constricts an artery. The spasm may be stopped with medication.

Heart attack

A heart attack is an emergency condition that requires treatment within 1 hour from the start of symptoms. Today, heart attack treatments help save lives and improve the quality of life for heart attack survivors.

Heart failure

• Left-sided heart failure
  Left-sided heart failure occurs when the heart has trouble pumping oxygen-rich blood to the rest of the body. Blood and fluid start accumulating in the lungs, causing shortness of breath.
  
• Right-sided heart failure
  Right-sided heart failure usually results from left-sided heart failure. The heart has trouble pumping blood to the lungs to pick up oxygen. Fluid starts building up in the feet, ankles, legs, and sometimes the abdomen.

Heart arrhythmias

• Tachycardia
  Tachycardia is a faster-than-normal heartbeat. Tachycardia is often a normal response to exercise or stress. In some cases, however, tachycardia may prevent the heart from pumping an adequate supply of blood to the rest of the body.
• Bradycardia
  Bradycardia is a slower-than-normal heartbeat. Although bradycardia may be normal in physically active people, the condition is sometimes due to a problem with the heart's electrical system.
• Atrial fibrillation
  Atrial fibrillation is the most common type of heart arrhythmia. It causes the heart's atria (upper chambers) to quiver quickly, preventing them from completely pumping out the blood. Blood may pool and clot inside the atria. If a blood clot breaks off and reaches the brain, it can cause a stroke (a blockage of blood flow to the brain).
• Ventricular fibrillation
  Ventricular fibrillation causes the heart's ventricles (lower chambers) to quiver instead of pumping blood out of the heart. The condition can be fatal if not treated immediately.