Coronary circulation – The Flow Of Blood Around The Heart

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How does blood flow through the heart?

The heart itself requires good blood flow in order for it to function normally. This blood flow is achieved with the blood flowing through small arteries that lie on the surface of the heart. These arteries are known as the coronary arteries. The circulation of blood through the coronary arteries is called the coronary circulation.

As a patient, if you suffer from chest pain or have some form of heart disease, you may require a test called a coronary angiogram. A coronary angiogram is a test that assesses the blood flow through the coronary arteries. It can pick up any narrowing is that may be present within the arteries and can help guide future treatment to prevent any damage to the heart muscle.

Once you have undergone a coronary angiogram, your cardiologist may discuss the findings with you. When doing so, they would talk about the different arteries of the heart and where the narrowings are. Of course, this can be rather confusing and this post is aimed towards explaining what the main arteries of the heart are and how important they are.

The coronary arteries

The coronary arteries arise from the larger artery that lies in the chest called the aorta. The aorta arises from the left ventricle and carries blood that is rich in oxygen to various parts of the body. It does so by dividing into numerous branches that supply the brain, kidneys, heart and other vital organs. The branches of the odour that supply the heart are called the coronary arteries.

On the left aspect of the aorta, a main branch arises called the left main stem branch. This is the primary branch that supplies the left side of the heart. The left main stem may divide further into two or three branches. These include

[list style=”arrow-right”] [li]Left anterior descending artery (LAD)[/li] [li]Circumflex artery (Cx)[/li] [li]Intermediate branch (ramus)[/li] [/list]
Coronary arteries
The coronary circulation. The LAD and RCA run round the front and right sides of the heart respectively. The circumflex artery runs around the back of the heart.

The left anterior descending artery supplies blood to the front of the heart  and the bottom of the left ventricle. In addition, it also supplies blood to the septum of the heart. The branches of the left anterior descending artery are called the diagonal arteries.

The circumflex artery supplies blood to the left atrium and the side of the heart including the back of the ventricle. The branches of the circumflex artery are called the obtuse marginal arteries.

The right coronary artery supplies blood to the right atrium,, right ventricle, bottom of the left ventricle and the back of the septum. The right coronary artery  terminates as the  posterior descending artery (PDA). In 15% of the cases, the posterior descending artery arises from the circumflex artery.

The intermediate branch arises only in  a small number of patients and supplies the same territories  that the circumflex  artery supplies in most cases.

The coronary veins

Just like anywhere in the body, the oxygenated blood i.e. blood that is poor in oxygen has to be carried into the lungs for enrichment. In the case of the heart, the oxygen poor blood is carried through the coronary veins. The coronary veins ultimately end in the right atrium.

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