What Is Coronary Artery Disease?

coronary artery disease (CAD) occurs when the arteries that supply blood to the heart muscle (coronary arteries) become hardened and narrowed. The arteries harden and become narrow due to the buildup of plaque on the inner walls or lining of the arteries (atherosclerosis). Blood flow to the heart is reduced as plaque narrows the coronary arteries. This decreases the oxygen supply to the heart muscle.

CAD is the most common type of heart disease. It is the leading cause of death in the U.S. in both men and women.

When blood flow and oxygen supply to the heart are reduced or cut off, you can develop:

• Angina . Angina is chest pain or discomfort that occurs when your heart is not getting enough blood.
• Heart Attack. A heart attack happens when a blood clot suddenly cuts off most or all blood supply to part of the heart. Cells in the heart muscle that do not receive enough oxygen-carrying blood begin to die. This can cause permanent damage to the heart muscle.

Over time, CAD can weaken your heart muscle and contribute to:

• heart failure. In heart failure, the heart is not able to pump blood to the rest of the body effectively. Heart failure does not mean that your heart has stopped or is about to stop working. But it does mean that your heart is failing to pump blood the way that it should.
• Arrhythmias. Arrhythmias are changes in the normal rhythm of the heartbeats. Some can be quite serious.

What Is Angina?

Angina, also called angina pectoris, is discomfort or pain in the chest that happens when not enough oxygen-rich blood reaches the muscle cells of the heart. Angina is not a disease, but a symptom of a more serious condition, usually coronary artery disease, an illness in which the vessels that supply blood to the heart become narrow or blocked. Coronary artery disease is usually caused by atherosclerosis, a condition in which fatty deposits (called plaque) build up along the inside walls of blood vessels. Although angina most commonly affects males who are middle-aged or older, it can occur in both sexes and in all age groups.

Arrhythmias Causes and incidence

Arrhythmias are caused by a disruption of the normal electrical conduction system of the heart. Normally, the four chambers of the heart (two atria and two ventricles) contract in a very specific, coordinated manner.

The signal for the heart to contract in a synchronized manner is an electrical impulse that begins in the sinoatrial node (also called the SA node), which is the body's natural pacemaker.