CORONARY ARTERIES
ISCHEMIA; ANGINA
HEART ATTACK; MYOCARDIAL INFARCTION

The heart is a muscle. Like all muscles and organs of the body, the heart needs oxygen in order to work. Oxygen is carried to the heart muscle by blood vessels. The word "cardiac" means heart. The blood vessels that carry oxygen to the heart muscle are called coronary arteries. They are locate on the outside of the heart muscle (Image 1).

Coronary artery disease occurs when fatty deposits collect inside the coronary arteries, narrowing the blood vessel diameter. This makes it difficult for blood to reach the heart muscle. If the narrowing becomes significant, the heart muscle will be deprived of oxygen.

Ischemia is a word used to describe a situation where there is not enough oxygen reaching the cells of the body. If the blood flow to the heart muscle is inadequate, cardiac ischemia can occur. Ischemia can cause chest pain. Chest pain due to ischemia is called angina. Blood flow to narrowed vessels can be improved by coronary artery bypass surgery or coronary angiography.

MYOCARDIAL INFARCTION
(also called "heart attack" or "MI")

If the heart muscle is deprived of oxygen for a prolonged period of time, an area of the heart muscle can die. Dead muscle is called an area of "infarction". When an area of the heart muscle dies, it is called "Myocardial Infarction" or "MI".

The most common cause for a myocardial infarction is blockage from a blood clot. Fatty disease of the blood vessels (called atherosclerosis) can promote clot formation. If a clot becomes large enough or breaks away from the wall of the vessel, it can block the flow of blood to an area of heart muscle.

Image 1: Heart muscle with normal coronary arteries.