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Coronary Blood Flow

Coronary Blood Flow

Author: Aaron Mullally

- Be able to identify the following coronary arteries: right main, left main, circumflex, anterior descending, posterior descending

- Be able to identify the following veins: coronary sinus, great cardiac, small cardiac, middle cardiac

- Know how much oxygen the heart needs to take in from arterial blood (what percentage)

- Know that the heart operates purely through aerobic metabolism

This packet discusses coronary circulation by providing an overview of the major coronary arteries and veins. These are easy but important to understand for various clinical purposes; the main one is identifying the location of myocardial infarctions (MI).

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Overview of Coronary Arteries

The heart is a highly demanding organ and like any other organ it needs a constant supply of blood. The coronary arteries are what supply the various areas of the heart with the oxygen it needs. Remember that the coronary arteries begin with the right and left main arteries which in turn branch to for new segments that supply other areas of the heart. The branches of the arteries are easy to understand because they are essentially named for the anatomic structures of the heart they pass over and supply or they are named based on how the travel. Two examples of this: circumflex artery: a branch of the left main coronary artery that circles to the posterior heart under the left atrium (circum = circular). Anterior descending: a branch of the left main coronary artery that descends down the anterior interventricular septum of the heart toward the apex.

The heart, like any other organ, also needs to have a blood drainage system i. e. veins. The veins are pretty easy to understand as well. Some of them have similar names to their arterial counterparts but most of them do have a little different nomenclature. These are also easy to remember though and always remember this one simple fact: veins and arteries always run parallel to one another just in opositte directions. Also remember that all of the cardiac veins collect on the underside of the right atrium and form the coronary sinus.

Blood flow to the heart is very critical due to its highly aerobic nature. The heart never stops working and demands a high amount of oxygen. Most tissues of the body only extract about 22% of oxygen out of arterial blood. The heart however extracts 100% of oxygen from the arterial blood that flows through it. This is why when people have an occlusion (plaque) in a coronary artery it doesn't take long to realize this. When there is a plaque build up in a coronary artery it is very easy for the parts of the heart behind the blockage to become ischemic quick; and don't forget that ischemia is a common cause of visceral pain. Plaque build up in these arteries can cause angina pectoris (chest pain) and myocardial infarctions (heart attacks).

Here is a useful website to check out:

Source: Self made by Aaron Mullally

Overview of Coronary Blood Flow with a Model

Here is a video overview of coronary arteries and veins with the use of a model

Source: Self made by bullharrier from youtube

Overview of Coronary Blood Flow with Diagrams

Here is an overview of coronary arteries and veins with the use of diagrams that I drew up

Source: Self made by bullharrier from youtube

Important Points to Understand

Here are a few key points to understand about coronary circulation

Source: Self made