Anatomy of the Heart

The heart is a muscular organ that is approximately the size of your closed fist. It is located behind the breastbone. The heart muscle consists of four chambers, four valves, and special blood vessels known as coronary arteries, that supply the muscle with the oxygen and nutrients it needs.

The heart acts like two separate pumps. After the body has used the oxygen in the blood, the veins carry the oxygen starved blood back to the right heart, where the blood enters the right atrium, travels through the tricuspid valve into the right ventricle which is the pumping chamber for the right side of the heart. The blood is then pumped out to the lungs through the pulmonary valve.

As the blood circulates through the lungs, it gets rid of waste products, like carbon dioxide, and picks up oxygen to deliver to all parts of the body. This oxygen-rich blood enters the left side of the heart through the pulmonary veins into the left atrium, travels through the mitral valve into the left ventricle where it is pumped through the aortic valve and out into the largest blood vessel of the body, the aorta, to all parts of the body.

The special blood vessels which supply the heart with the necessary oxygen and nutrients are called coronary arteries. The two main coronary arteries, the left coronary artery and right coronary artery, begin in the aorta just above the aortic valve. The left coronary artery has two main branches: the Left Anterior Descending (LAD) and the Circumflex (CX). The right coronary artery (RCA) is primarily a single vessel which curves near the base of the heart and divides into two branches, the larger branch being called the Posterior Descending Artery (PDA). The coronary arteries lie on the surface of the heart, with smaller branches going into the heart muscle.

Over the course of a person's lifetime many influences can cause one or more of these arteries to become narrowed or blocked with deposits known as atherosclerotic plaque. When this occurs, the heart cannot receive enough oxygen to do its work properly. If the artery becomes totally blocked, a heart attack (myocardial infarction or MI) can occur.
Atherosclerosis is one of the leading causes of heart disease and is characterized by a buildup of plaque and other materials which cause the vessels to become narrow. This decrease in the inner diameter of the artery will restrict blood flow through the vessel. Although the exact cause of atherosclerosis is not known, there are certain risk factors which are often seen in patients with coronary artery disease. These factors include high blood pressure, smoking, being overweight, a high-fat diet, lack of a regular exercise program, diabetes, and/or a family history of heart disease.

You may have experienced symptoms of atherosclerosis which caused you to seek your doctors attention. You may have felt fatigue, shortness of breath, angina (chest pain which can often be felt in the jaw, arm or back), uneven or rapid heartbeats (palpitations), and/or dizziness.

To provide your doctor with a better understanding of how well your heart is working, you have probably already had some other tests, such as an electrocardiogram (EKG), a treadmill or stress test, a chest x-ray, and blood tests.

A cardiac catheterization is the most thorough test you can have to determine how well your heart is working. This test will let your doctor see if there are any narrowings and/or blockages of the coronary arteries and, if so, where they are located. He can see if the heart valves are opening and closing properly, and study the overall pumping efficiency of the heart muscle itself.

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