Introduction

Introduction

The heart is the human body's hardest working organ. Throughout life it continuously pumps blood enriched with oxygen and vital nutrients through a network of arteries to all parts of the body's tissues. In order to perform the arduous task of pumping blood to the rest of the body, the heart muscle itself needs a plentiful supply of oxygen-rich blood, which is provided through a network of coronary arteries. These arteries carry oxygen-rich blood to the heart's muscular walls (the myocardium).

Coronary Artery Disease

Coronary artery disease is the most common cause of heart attacks. Coronary artery disease is the end result of a complex process called atherosclerosis (commonly called "hardening of the arteries"). This causes blockage of arteries (ischemia) and prevents oxygen-rich blood from reaching the heart. A full-blown heart attack occurs when blood flow to the myocardium is blocked and tissue death occurs from loss of oxygen, severely damaging the heart. The medical term for heart attack is myocardial infarction. [For more information see In-Depth Report #3: Coronary artery disease.]

Click the icon to see an image of atherosclerosis.

Heart Attack

Heart attack (or myocardial infarction) is the most serious outcome of atherosclerosis. It can occur as a result of one or two effects of atherosclerosis:

(1) If the artery becomes completely blocked and ischemia becomes so extensive that oxygen-bearing tissues around the heart die.

(2) If the plaque itself develops fissures or tears. Blood platelets adhere to the site to seal off the plaque, and a blood clot (thrombus) forms. A heart attack can then occur if the formed blood clot completely blocks the passage of oxygen-rich blood to the heart.

Click the icon to see an image of an acute myocardial infarction.

Angina

Angina is the primary symptom of coronary artery disease and is typically experienced as chest pain. There are two kinds of angina:

• Stable Angina is predictable chest pain that can usually be managed with lifestyle measures and medications, such as low-dose aspirin.
• Unstable angina is a much more serious situation than stable angina that is often an intermediate stage between stable angina and a heart attack. Unstable angina is part of a condition called acute coronary syndrome.