What Is Heart Disease: Heart Disease

Content provided by the Faculty of the Harvard Medical School

What is heart disease?

When people speak of heart disease, they usually mean the condition more accurately described as coronary artery disease. This is a narrowing of the coronary arteries that reduces blood flow to the heart muscle, which can cause chest pain (angina) or a heart attack (myocardial infarction). Coronary artery disease is by far the most common type of cardiovascular disease (see "Heart disease in America," below). It's also the most preventable.

The coronary arteries play a vital role by supplying the heart with oxygen-rich blood. The heart muscle depends on two main arteries, the right and left coronary arteries, for its entire supply of blood and oxygen. Like the branches of a tree, each main artery divides into progressively smaller channels that carry blood to the heart muscle cells. Either of these arteries or any of their branches can be narrowed by a buildup of fatty plaque, known medically as atherosclerosis (see Figure 1). This term combines two Greek words, athere (porridge) and sclerosis (hardening). The name is accurate: In atherosclerosis, the artery walls become filled with soft, mushy deposits that eventually make the artery hard, stiff, and narrow.

Figure 1: Your heart's "weakest links" Blockage can occur in any of your coronary arteries. Two common sites are the right coronary artery (A) and the left anterior descending artery (B). When blockages occur in these locations, heart damage may result in the adjoining shaded areas.

These deposits can restrict blood flow, resulting in ischemia, or oxygen deprivation. A partial or temporary interruption in blood supply, causing mild ischemia, will injure the heart muscle and can produce angina. Complete or prolonged interruption of blood flow, causing severe or prolonged ischemia, leads to the death of heart muscle cells that constitutes a heart attack. Ischemia can impair the heart's ability to pump blood, interrupt its normal pumping rhythm, or even produce a heart attack.

Coronary artery disease can also produce congestive heart failure and abnormal heart rhythms (arrhythmias). Congestive heart failure occurs when the heart can't pump sufficient blood, producing shortness of breath, fatigue, and fluid accumulation. Arrhythmias can produce palpitations, fainting, and even sudden death.

Last updated:	May 03, 2007