Coronary Artery Disease

What is coronary artery disease?
The coronary arteries provide the heart with blood. The heart muscle needs a constant supply of oxygen-rich blood to function normally.

Fatty deposits, or plaques, attach to the walls of the arteries. As the plaques enlarges, it may cause chronic narrowing within the channel of the coronary artery. The plaque's hard, outer shell may rupture and release disc-shaped particles in the blood that aid clotting called platelets. This process can cause blood clots to form within the artery and block blood flow.

If an artery becomes narrowed, the heart muscle is deprived of oxygen and nutrients (this is called ischemia) in the region below the blockage. As a result, heart muscle cells die, causing permanent damage to the heart. This is called a myocardial infarction (MI) or heart attack. If an artery is completely blocked, the heart muscle loses oxygen and nutrients (this is called ischemia) in the region below the blockage. As a result, heart muscle cells die, causing permanent damage to the heart. This is called a myocardial infarction (MI) or heart attack.

What is a Heart Attack?
A heart attack, also known as myocardial infarction, is permanent damage to the heart muscle caused by a lack of blood supply to the heart (ischemia) for an extended time period. The severity of damage varies from normal, mild, to severe. The plaque's hard, outer shell may rupture and release disc-shaped particles in the blood that aid clotting called platelets. This process can cause blood clots to form within the artery and block blood flow.

A heart attack can be caused by an arterial plaque rupture, but also occur from a spasm in a coronary artery. During a spasm, the coronary arteries temporarily constrict or spasm, causing a lack of blood supply to the heart muscle. It may occur at rest and can even occur in people without significant coronary artery disease. If coronary artery spasm occurs for a long period of time, a heart attack can occur.

Each coronary artery supplies blood to a region of the heart muscle. If an artery is occluded (blocked) there is no blood supply to that region. The amount of damage to the heart muscle depends on the size of the area supplied by the blocked artery and the time between injury and treatment. Rapid treatment to open the blockage is critical to lessen the amount of damage.

The heart muscle has a limited ability to heal shortly after a heart attack. Scarring of the heart muscle may occur in the damaged area of the heart. The new scar tissue does not pump as well as healthy heart muscle tissue. The amount of lost pumping ability depends on the size and location of the scar.