Coronary arteries and the risk of heart attack

Coronary arteries are branches of aorta and their main task is to supply oxygenated blood to the heart itself. If they get clogged there is a risk of heart attack and stroke. In this post we shall describe these risk factors in more details.

Coronary artery branches

The heart is usually supplied from two coronary arteries – the right one and the left one. Both of them run in a sulcus called coronary sulcus, which actually separates heart ventricles from heart atria.

Branches of left coronary artery are as follows:

Anterior descending branch (or LAD – Left anterior descending artery) – Diagonal arteries (D1, D2, etc...) – left conus (arteriosus) artery – left atrial branches circumflex branch – left marginal artery – left posterolateral artery (present in 55% cases).

Branches of right coronary artery are as follows:

Sinoatrial node artery (SAN) - Right conus (arteriosus) artery - Right atrial branches - Right marginal artery - Posterior descending branch - Atrioventricular node branch  - Right posterolateral artery (present in 45% cases).

The arteries in bold may get clogged and cause myocardial infarction.

Coronary arteries, myocardial bridges and risk of myocardial infarction

Coronary arteries usually run on the surface of the coronary sulcus and are covered by some fatty tissue. However sometimes a myocardial bridge (e.g. a small portion of the heart muscle) may grow over the coronary artery and cause its narrowing or even clogging due to compression. Smaller bridging (vincula) are normally undetectable and they usually do not cause any blood flow problems as coronary arteries are filled during myocardial relaxation (diastole).

On the other hand, larger bridges (ponticles) may cause coronary artery clogging. This mainly concerns Anterior descending branch (LAD) or Diagonal arteries.

What else increases the risk of coronary artery related heart attack?

In addition to myocardial bridges there are also some more important risk factors of coronary artery clogging. One of them is atherosclerosis, which is closely related to high cholesterol levels in blood. Too much cholesterol in blood may block auto-repairing functionality of arteries and lead to atherosclerotic plaque formation in the artery. This of course results in arterial stenosis and clogging. Also some conditions, such as diabetes mellitus, increase the risk of heart attack due to the fact that they compromise auto-repairing functionality of blood vessels and make them fragile.