Coronary Artery Disease

What are the coronary arteries?

The coronary arteries are small vessels located around the outer surface of the heart which deliver blood, with its oxygen and nutrients, to the heart muscle cells.  There are two coronary arteries – the Right and the Left Coronary Arteries – which are the first vessels that branch off the aorta, near its base, and surround the heart muscle.  The Left Coronary Artery branches quickly into major vessels (like a wishbone) – the Left Anterior Descending Artery and the Left Circumflex Artery – so we often refer to the heart’s “three” coronary arteries:  the Right Coronary Artery (RCA), the Left Anterior Descending Artery (LAD), and the Left Circumflex Artery (LCX).  In our western culture, there is a strong tendency to develop atherosclerosis in our coronary arteries. 

What is atherosclerosis?

Atherosclerosis (or arteriosclerosis) is the abnormal build up of fatty deposits called “plaque” in the walls of arteries.  In the presence of certain pre-disposing conditions such as hypertension, hypercholesterolemia, diabetes, obesity, smoking, or genetic factors (family history of premature coronary artery disease), a biochemical process ensues that leads to the deposition of cholesterol and migration of certain inflammatory cells into the inner lining of the arterial wall.  Certain cells and chemicals interact in the arterial lining, and plaques form.  As the plaques grow in size, they encroach on the inner space (called the “lumen”) of the artery, impeding blood flow down that artery. 

What is coronary artery disease?

When atherosclerosis develops in the coronary arteries, it is called “coronary artery disease” (CAD).  Plaque may form in one single spot in the coronary arteries or several spots or may develop throughout the course of these arteries.  The plaque may be mild, moderate, or severe in the degree of obstruction it causes in the arteries.  Generally, the plaque has to become at least 70% obstructive before it causes any symptoms, though occasionally people with less severe blockage (e.g., 50%) will have symptoms, and sometimes people with very severe blockages (e.g., 90%) will surprisingly have no symptoms at all. 

What are the consequences of coronary artery disease?

People who have significant coronary artery disease (generally having at least one blockage in their coronary arteries that exceeds 70% narrowing) are prone to develop symptoms caused by coronary insufficiency that develops when the delivery of blood to an area of heart muscle during a period of stress for the heart is inadequate due to the narrowing in that vessel.  These symptoms of insufficiency of coronary blood flow are referred to as “angina” and occur with a variety of different descriptions.  The classic description of angina is the development of pressure, aching, or a constricting sensation in the mid chest provoked by exertion or emotional stress.  This discomfort may radiate to one or both shoulders, down one or both arms, and may be associated with shortness of breath.  Alternatively, the location of discomfort may be in one of the shoulders, uppers arms, elbows, or forearms, neck, jaw, shoulder blade, or mid upper back.  The symptoms generally last for several minutes, resolving with rest or relaxation.  Other descriptions of angina include indigestion, a burning sensation in the mid chest, severe backache or toothache, or severe shortness of breath.  Occasionally people may have significant coronary artery but have no symptoms of angina at all, and this is called “silent” coronary insufficiency.  In some patient with severe coronary artery disease, profound coronary insufficiency may lead to cardiac rhythm disturbances which may potentially result in sudden death.