Editing Cardiology (section)

=== Coronary circulation ===
{{Main|Coronary circulation}}

Coronary circulation is the circulation of blood in the [[blood vessel]]s of the [[heart muscle]] (the myocardium). The vessels that deliver oxygen-rich blood to the myocardium are known as coronary arteries. The vessels that remove the deoxygenated blood from the heart muscle are known as cardiac veins. These include the [[great cardiac vein]], the [[middle cardiac vein]], the [[small cardiac vein]] and the [[anterior cardiac veins]].

As the left and right coronary arteries run on the surface of the heart, they can be called epicardial coronary arteries. These arteries, when healthy, are capable of autoregulation to maintain coronary blood flow at levels appropriate to the needs of the heart muscle. These relatively narrow vessels are commonly affected by [[atherosclerosis]] and can become blocked, causing [[Angina pectoris|angina]] or myocardial infarction (a.k.a., a heart attack). The coronary arteries that run deep within the myocardium are referred to as subendocardial.

The coronary arteries are classified as "end circulation", since they represent the only source of blood supply to the myocardium; there is very little redundant blood supply, which is why blockage of these vessels can be so critical.