The coronary arteries are the arteries that supply blood to the heart. The coronary circulation is divided into the right and the left sides. Whichever side delivers blood to the bottom part of the heart is considered to be the “dominant” side. The right side is dominant in 70 percent of the population. The left is dominant in 25 percent of people, and a minority of people have what is called a “co-dominant” circulation. This means that the bottom part of the heart receives blood from both sides. This is considered to be a protective advantage to the person. The coronary arteries are especially sensitive to the development of atherosclerosis.
Most people have four major branches in their coronary arteries:
The “RCA” or right coronary artery: This branch usually supplies blood to the right ventricle and the bottom of the heart.
The “LM” or left main artery: This is the short but very important first part of the left circulation. It divides into the LCx and the LAD.
The “LCx” or circumflex artery: This branch supplies blood to the left wall of the heart. It usually has subdivisions called the obtuse marginals or “OMs.” Heart attacks caused by a blocked circumflex are sometimes hard to detect in ECG, because the ECG does a poor job of detecting electricity in the left side of the heart.
The “LAD“: left anterior descending artery – This artery supplies blood to the largest amount of muscle mass in the heart: the left ventricle. This branch of the coronary circulation is popularly referred to as “the widow-maker,” because a heart attack resulting in its blocking has a high mortality rate since it risks the largest amount of heart.« Back to Glossary Index