What Is CAD?

Coronary artery disease (CAD) starts with a buildup of fatty deposits in the lining of the arteries supplying blood to the heart. Due to this process -- called atherosclerosis -- the narrowed arteries can't keep up a healthy flow of blood to the heart. As CAD worsens, heart function is increasingly affected. CAD is sometimes called "hardening of the arteries."

Normal Heart/Vessel Anatomy

Located in the chest between the lungs, the heart is the strongest muscle in the body. Its function is to receive oxygen-rich blood from the lungs and pump it out through various arteries to all the organs of the body. Three main coronary arteries supply blood to the heart: the right coronary artery (RCA), the left anterior descending (LAD) artery, and the circumflex (Cfx) artery.

Atherosclerosis

In atherosclerosis, cholesterol carried in the blood builds up fatty deposits (plaques) in the artery lining over time. The resulting artery narrowing, called a stenosis, can eventually reduce blood flow to the heart.

Plaque Formation

Plaque formation and stenosis take place over a period of years. The process begins with the formation of a fatty streak that can appear as early as adolescence.

Doctors describe an individual patient's stenosis by its extent. This is represented as a "narrowing percentage." This image shows a 95% stenosis.

Coronary Artery Blockage and Heart Attack

As coronary artery narrowing progresses, the risk increases that a clot will form on top of the plaque and totally block the artery. This keeps oxygen and vital nutrients from the heart muscle, and the affected tissues die (called an infarct). The heart can no longer function, and a heart attack (myocardial infarction, or MI) results.

Angioplasty

Used to treat advanced CAD, angioplasty involves inserting a tube (catheter) into the coronary artery and inflating a surgical balloon at the point of stenosis. This helps restore the natural artery opening and increases blood flow.

Stent

Sometimes a special mesh-like device called a stent is left in place after the angioplasty to help keep the artery open and the blood flowing to the heart.

Coronary Bypass Surgery

When angioplasty is not advisable for treating a patient's advanced CAD, coronary artery bypass may be done. This surgical procedure creates a new route for blood flow around the stenosis using either a piece of vein (graft) from the patient's leg or an artery from the chest (graft) to effectively "bypass" the narrowed coronary artery segment.