Heart Disease, Coronary

Coronary Heart Disease

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What are the coronary arteries?

Coronary arteries supply blood to the heart muscle. Like all other tissues in the body, the heart muscle needs oxygen-rich blood to function, and oxygen-depleted blood must be carried away. The coronary arteries consist of two main arteries: the right and left coronary arteries. The left coronary artery system branches into the circumflex artery and the left anterior descending artery.

What are the different coronary arteries?

The two main coronary arteries are the left main and right coronary arteries. The left main coronary artery (LMCA), which divides into the left anterior descending artery and the circumflex branch, supplies blood to the left ventricle and left atrium. The right coronary artery (RCA), which divides into the right posterior descending and acute marginal arteries, supplies blood to the right ventricle, right atrium, sinoatrial node (cluster of cells in the right atrial wall that regulates the heart's rhythmic rate), and atrioventricular node (AV node, a cluster of cells between the atria and ventricles that regulate the electrical current).

Additional arteries branch off the left main coronary artery to supply the left side of the heart muscle with blood. These include the following:

• Circumflex artery (Cx). The circumflex artery branches off the left coronary artery and encircles the heart muscle. This artery supplies blood to the lateral side and back of the heart.

• Left anterior descending artery (LAD). The left anterior descending artery branches off the left coronary artery and supplies blood to the front of the left side of the heart.

Smaller branches of the coronary arteries include: acute marginal (AM), posterior descending (PDA), obtuse marginal (OM), septal perforator (SP), and diagonals.

Why are the coronary arteries important?

Since coronary arteries deliver blood to the heart muscle, any coronary artery disorder or disease can have serious implications by reducing the flow of oxygen and nutrients to the heart, which may lead to a heart attack and possibly death. Atherosclerosis (a buildup of plaque in the inner lining of an artery causing it to narrow or become blocked) is the most common cause of heart disease.

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What is coronary artery disease?

Coronary heart disease, or coronary artery disease (CAD), is characterized by the accumulation of fatty deposits along the innermost layer of the coronary arteries. The fatty deposits may develop in childhood and continue to thicken and enlarge throughout the life span. This thickening, called atherosclerosis, narrows the arteries and can decrease or block the flow of blood to the heart.

What are the risk factors for coronary artery disease?

Risk factors for CAD often include:

• High LDL cholesterol, high triglycerides levels, and reduced HDL cholesterol

• High blood pressure (hypertension)

• Physical inactivity

• Smoking

• Obesity

• High saturated fat diet

• Diabetes

Controlling risk factors is the key to preventing illness and death from CAD.

What are the symptoms of coronary artery disease?

The symptoms of coronary heart disease will depend on the severity of the disease. Some persons with CAD have no symptoms, some have episodes of mild chest pain or angina, and some have more severe chest pain.

If too little oxygenated blood reaches the heart, a person will experience chest pain called angina. When the blood supply is completely cut off, the result is a heart attack, and the heart muscle begins to die. Some persons may have a heart attack and never recognize the symptoms. This is called a "silent" heart attack.

When symptoms are present, each person may experience them differently. Symptoms of coronary artery disease may include:

• Heaviness, tightness, pressure, and/or pain in the chest--behind the breastbone

• Pain radiating in the arms, shoulders, jaw, neck, and/or back

• Shortness of breath

• Weakness and fatigue

How is coronary artery disease diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for coronary artery disease may include any, or a combination of, the following:

• Electrocardiogram (ECG or EKG). A test that records the electrical activity of the heart, shows abnormal rhythms (arrhythmias or dysrhythmias), and detects heart muscle damage.

• Stress test (usually with ECG; also called treadmill or exercise ECG). A test that is given while a patient walks on a treadmill to monitor the heart during exercise. Breathing and blood pressure rates are also monitored. A stress test may be used to detect coronary artery disease, and/or to determine safe levels of exercise following a heart attack or heart surgery.

• Cardiac catheterization. With this procedure, X-rays are taken after a contrast agent is injected into an artery to locate the narrowing, occlusions, and other abnormalities of specific arteries.

• Nuclear scanning. Radioactive material is injected into a vein and then is observed using a camera as it is taken up by the heart muscle. This indicates the healthy and damaged areas of the heart.

Treatment for coronary heart disease

Specific treatment will be determined by your doctor based on:

• Your age, overall health, and medical history

• Extent of the disease

• Your tolerance for specific medications, procedures, or therapies

• Expectations for the course of the disease

• Your opinion or preference

Treatment may include:

• Modification of risk factors. Risk factors that may be modified include smoking, elevated cholesterol levels, elevated blood glucose levels, lack of exercise, poor dietary habits, being overweight/obese, and elevated blood pressure.

• Medications. Medications that may be used to treat coronary artery disease include:

  • Antiplatelet medications. Medications used to decrease the ability of platelets in the blood to stick together and cause clots. Aspirin, clopidogrel (Plavix), ticlopidine (Ticlid), and prasugrel are examples of antiplatelet medications.

  • Anticoagulants. Also described as "blood thinners," these medications work differently than antiplatelet medications to decrease the ability of the blood to clot. An example of an anticoagulant is warfarin (Coumadin).

  • Antihyperlipidemics. Medications used to lower lipids (fats) in the blood, particularly Low Density Lipid (LDL) cholesterol. Statins are a group of antihyperlipidemic medications, and include simvastatin (Zocor), atorvastatin (Lipitor), and pravastatin (Pravachol), among others. Bile acid sequestrants--colesevelam, cholestyramine and colestipol--and nicotinic acid (niacin) are two other types of medications that may be used to reduce cholesterol levels.

  • Antihypertensives. Medications used to lower blood pressure. There are several different groups of medications which act in different ways to lower blood pressure

• Coronary angioplasty. With this procedure, a balloon is used to create a bigger opening in the vessel to increase blood flow. Although angioplasty is performed in other blood vessels elsewhere in the body, percutaneous coronary intervention (PCI) refers to angioplasty in the coronary arteries to permit more blood flow into the heart. PCI is also called percutaneous transluminal coronary angioplasty (PTCA). There are several types of PCI procedures, including:

  • Balloon angioplasty. A small balloon is inflated inside the blocked artery to open the blocked area.

  • Coronary artery stent. A tiny coil is expanded inside the blocked artery to open the blocked area and is left in place to keep the artery open.

  • Atherectomy. The blocked area inside the artery is cut away by a tiny device on the end of a catheter.

  • Laser angioplasty. A laser used to "vaporize" the blockage in the artery.

• Coronary artery bypass. Most commonly referred to as simply "bypass surgery," this surgery is often performed in people who have angina (chest pain) and coronary artery disease (where plaque has built up in the arteries). During the surgery, a bypass is created by grafting a piece of a vein above and below the blocked area of a coronary artery, enabling blood to flow around the obstruction. Veins are usually taken from the leg, but arteries from the chest or arm may also be used to create a bypass graft.