Coronary Artery

Original Editor - Rania Nasr

Top Contributors - Lucinda hampton, Rania Nasr and Kim Jackson  

Introduction

The coronary arteries arise from the coronary sinuses immediately distal (superior) to the aortic valve and supply the myocardium with oxygenated blood

• This is a crucial function for myocardial function and subsequently homeostasis of the body.

They branch and encircle the heart to cover its surface with a lacy network, perhaps resembling a slightly crooked crown.

Gross Anatomy

The typical configuration consists of two coronary arteries, arising from the left posterior and right anterior aortic or coronary sinuses respectively, in the proximal ascending aorta. These are the only two branches of the ascending aorta.

1. Left coronary artery (LMCA): The left coronary artery has a short common stem (and is hence often referred to as the left main coronary artery), that bifurcates into the left circumflex artery (LCx), which courses over the left atrioventricular groove, and the left anterior descending artery (LAD), which passes towards the apex in the anterior interventricular groove.
2. Right coronary artery (RCA): The right coronary artery courses in the right atrioventricular groove to the inferior surface of the heart, whereupon it turns anteriorly at the crux as the posterior descending artery (PDA) in right dominant circulation.

Occasionally there is a trifurcation (in ~15%), with the third branch, the ramus intermedius, arising inbetween the LAD and LCx. In left dominant hearts, the LCx supplies the posterior descending artery (PDA).

Coronary Dominance

• Most hearts are right dominant (60%) where the PDA is supplied by the RCA.
• However, up to 20% of hearts may be left dominant, where the PDA is supplied by the LAD or LCx, or codominant, where a single or duplicated PDA is supplied by branches of both the RCA and LAD/LCx (20%).

Supply

The RCA emerges from the anterior ascending aorta and supplies blood to the right atrium, right ventricle, SA node, and AV node.

• It descends into smaller branches including the right posterior descending artery (PDA) and acute marginal artery.

• In conjunction with the left anterior descending artery (LADA), the RCA helps supply blood to the septum of the heart.

The LMCA gives off two major branches; the left anterior descending (LAD) and the left circumflex (LCx) coronary arteries, which supply blood to the left atrium and left ventricle.  

• The LAD supplies blood to the front and the left side of the heart.  
• The circumflex artery is responsible for blood supply to the left atrium and the posterior-lateral aspect of the left ventricle. 

Clinical Relevance

Like other arteries, the coronaries may be subject to arteriosclerosis (hardening of the arteries) causing Coronary artery disease (CAD, also called coronary heart disease, or CHD).

Arteries that have become extremely narrow can cause shortness of breath and angina during physical activity. If a coronary artery suddenly becomes completely blocked, it can result in a Myocardial Infarct/heart attack.

Bypass surgery - A surgical procedure performed to improve blood supply to the heart by creating new routes for blood flow when one or more of the coronary arteries become obstructed. The surgery involves removing a healthy blood vessel from another part of the body, such as the leg, and grafting it onto the heart to circumvent the blocked artery. Those most often bypassed today include the right coronary artery, the posterior descending coronary artery, the left main coronary artery, the left anterior descending coronary artery and the left circumflex coronary artery. Plaques obstructing the coronary arteries may also be treated by balloon angioplasty, stents, and other techniques.

Related pages

Acute Coronary Syndrome

Physical Activity and Cardiovascular Disease

Cardiac Rehabilitation

Myocardial Infarction

Atrial Fibrillation