What are coronary arteries?

The coronary arteries.


Coronary arteries (coloured red on the picture above) supply your heart with blood, and problems here can lead to heart attacks.


  1. Coronary arteries are tubes that supply the heart muscle with blood (which has oxygen and various nutrients to keep the muscle alive).
  2. There are three main coronary arteries – the left anterior descending (LAD), the left circumflex (LCx) and the RCA (right coronary artery).
  3. If these coronary arteries get plaque and become narrowed, the blood supply to the heart muscle can get worse, leading to angina, shortness of breath and other symptoms.


Your heart is a pump, designed to supply the body with blood – the left side (specifically, the left ventricle) pumps blood full of oxygen around your body to your muscles and organs. The heart needs to supply its own muscle with blood though, and it does this through the coronary arteries.

Normally, the main pumping chamber in the heart pumps into a big tube called the aorta. Many branches come off this main tube and go and provide oxygen-rich blood to the brain, abdominal organs, muscles – everything. The very first branches however are the coronary arteries, so blood comes out of the pumping chamber, and immediately takes a U-turn and supplies the heart muscle itself.

There is one on each side – the left main (LM) and the right coronary artery (RCA)The left main divides into the left anterior descending (LAD), which runs down the front of your heart, and the left circumflex (LCx), which runs down the side. The right coronary artery heads down the right side and then the bottom, and in most people, it also supplies the back of your heart.

Image by Blausen Medical.


These arteries can develop narrowings due over time due to fatty deposits – plaque – which can then either gradually reduce the blood supply (ischaemia, leading to angina) or suddenly rupture and block off the artery, causing a serious heart attack. The process that causes plaque to build up is called atherosclerosis. Each of the arteries are important, but having a plaque in the left main is very dangerous, as the entire left side of the heart is supplied by it. The LAD is also critical even on its own, as the muscle at the front of the heart (anterior) is very important.

Each of these three main arteries (LAD, LCx and RCA) have sub-branches that supply various parts of the heart. During a heart attack, the ECG can sometimes (but not always) tell which artery has a problem.

Although most people have the same three arteries, there is a bit of variation. Certain arteries can come off the opposite side to what we expect, or have unusual branches or courses. A coronary angiogram is the most definitive test to show the blood flow through the arteries themselves, but CT coronary angiography can also show them.

When you have narrowings in your heart arteries, the condition is called coronary artery disease. If these narrowings are significant enough to stop enough blood getting to the heart muscle (ischaemia), then the condition is called ischaemic heart disease.



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