Location:
The coronary system is comprised of arteries, arterioles, capillaries, venules and veins. The coronary arteries originate as the right and left main coronary arteries which exit the ascending aorta just above the aortic valve (coronary ostia). These two branches subdivide and course over the surface of the heart (epicardium) as they traverse away from the aorta. These arteries divide into progressively smaller branches that then progress inward to penetrate the epicardium and supply blood to the transmural myocardium. Coronary arteries eventually branch into arterioles. Arterioles then branch into innumerable capillaries through which blood will begin its flows back to the cardiac chambers (see also the Coronary System Tutorial).

Function:
The coronary arteries supply blood to the myocardium (heart tissue) itself: e.g., coronary capillaries deliver oxygenated blood (nutrients) to all of the heart’s cells.

Importance in cardiovascular diseases:
Abnormal function leads to coronary ischemia, angina, reduced performance and/or infarction; atherosclerotic plaques can form in the coronary arteries, which can lead to regionally occluded flows. Changes in electrocardiograms can be recorded within beats when there is inadequate blood flow delivered to a region of the heart. More specifically, whenever coronary blood flow falls below what is required to meet metabolic needs, the myocardium is considered ischemic; the pumping capability of the heart is impaired, and there are associated changes in electrical activity (e.g., increased risk of fibrillation).

Importance in device delivery:
Percutaneous transluminal coronary angioplasty is a procedure during which a balloon catheter is introduced into the narrowed portion of the coronary artery lumen and inflated to reopen the artery to allow the return of normal blood flow. During this procedure, often a coronary stent is also placed such that restenosis of the artery is significantly delayed. A stent is a device made up of wire mesh that provides scaffolding to support the wall of the artery and keep its lumen open and free from the buildup of plaque. Coronary artery bypass graft (CABG) surgery is performed to reroute blood flow through a new artery or vein that is grafted around diseased sections of your coronary arteries to increase blood flow to the heart muscle tissue. Stem cell or other biologic therapies can be delivered to the heart via the coronary vasculature.