arteries are the ones that we try to keep clear by eating
a healthy diet. If Coronary arteries are blocked a heart attack
The heart, just like any other
organ, requires blood to supply it with oxygen and other nutrients
so that it can do its work. The heart does not extract oxygen
and other nutrients from the blood flowing inside it -- it
gets its blood from coronary arteries that eventually carry
blood within the heart muscle. Approximately 4-5% of the blood
output of the heart goes to the coronary arteries (7 ½
ounces/minute or 225 ml/min).
There are two main coronary
arteries (figure 6) - The Left Main Coronary artery (1) and
the Right Coronary Artery (2) which arise from the Aorta.
The Left Main Coronary Artery divides into the Left Anterior
Descending Branch (3) and the Left Circumflex Arteries (4).
Each artery supplies blood to different parts of the heart
muscle and the electrical system.
The heart also has veins that
collect oxygen-poor blood from the heart muscle. Most of the
major veins of the heart (great cardiac vein, small cardiac
vein, middle cardiac vein, posterior vein of the Left Ventricle,
and oblique vein of the Left Atrium) drain into the coronary
sinus which opens into the Right Atrium.
Coronary artery disease is caused
by a blockage in one of the coronary arteries. When a coronary
artery is partially blocked, that artery cannot supply enough
blood to the heart muscle to meet its needs during exertion.
When someone with coronary artery disease exerts himself or
herself, it causes chest pain. This is due to lack of blood
and oxygen to that part of the heart muscle and is called
angina. If the obstruction worsens (more frequent angina episodes,
with less exertion) a condition called unstable angina can
occur. A heart attack happens when a coronary artery is completely
blocked and no blood or oxygen is getting to the heart muscle
served by that artery. This also causes chest pain and causes
death to the heart muscle served by that artery.