Explaining the make up of the coronary artery anatomy can be a complicated business. There are two coronary arteries – the left and the right. The left divides into two major systems very quickly which gives us a total of three systems of arteries taking blood to the heart. One system is down the front, one is down the side and the third is to the undersurface.

Left anterior descending

The artery down the front wall of the heart is the left anterior descending (LAD) system and is the most important coronary vessel. If a person block this artery acutely they are three times more likely to die than if they were to block any other part of the coronary artery anatomy.

Right coronary artery

The second most important system is the right coronary artery (RCA). This vessel courses over the heart behind the breastbone to reach the inferior surface of the heart.

Circumflex

Finally, the third system is called the circumflex (Cx) and supplies the left lateral wall of the heart. Usually the RCA is larger and more important than the Cx but sometimes this is reversed and the RCA can be relatively small and unimportant - medically it is called non-dominant.

To summarise the coronary artery anatomy there are two coronary arteries which become three coronary systems - each of which breaks up into several terminal branches. These terminal vessels can vary a lot between different people – so much so that one person can really only have three significant terminal branches where another can have as many as six or seven!

The initial 2cm of the left coronary artery before it divides into LAD and Cx is called the left main stem (LMS). Narrowings in this area are of critically importance as they are highly fatal unless treated - 12 per cent of people with this type of narrowing die from it each year if nothing is done. To put it another way, if 100 people with a LMS narrowing were to stand in a line then each month one of them would die; after five years 60 of them would be dead and only 40 still alive!

This explains why sometimes people are offered surgery even though they may have no symptoms at all – it is generally better to have a low risk operation now than to wait for the disease to strike.

What every patient really wants is to wait and have their heart surgery the day before their fatal heart attack! Sadly, we cannot predict the where and when it will be, so patients will always be asked to screw up their courage and accept the offer of surgery whilst they feel relatively well in themselves.