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Cardiac Bypass Surgery

When Is Bypass Surgery Offered?

Tuesday, March 20, 2012 - 17:38

Contributing Author: Guy Slowik FRCS

There are two main coronary arteries supplying blood to the heart, the left coronary artery and the right coronary artery. The left main coronary artery, which splits into two further branches known as the left anterior descending artery and the left circumflex artery, supplies most of the heart with blood; thus if it is diseased, can cause major problems. The right coronary artery supplies blood to the right side of the heart and the lower part of the left side of the heart.

Most people with angina have blockages in one or more of these arteries and/or their branches. A cardiologist (heart specialist) will perform various tests to determine the location and extent of the blockage.

Bypass surgery is usually performed when a person has two or three blood vessels with blockages, or when the major vessel has a severe blockage. Therefore, bypass surgery may be advised in the following situations:

  • When there is severe narrowing of the left main coronary artery (because this major artery branches into several others, putting too much of the heart at risk if the angioplasty were to fail)
  • If there is severe narrowing of any three arteries in a person who also has a weakly pumping heart
  • If there is severe narrowing of the left anterior descending artery and at least one other coronary artery, plus either diabetes or a weakly pumping heart
  • Following failed coronary angioplasty, a procedure performed to widen a narrowed coronary artery by inserting a balloon-tipped tube into the artery and inflating the balloon.

    For further information about angioplasty, go to Angioplasty.

What Is Coronary Artery Disease?

Coronary artery disease - also known as coronary heart disease (CHD) or ischemic heart disease (IHD) - affects most people as they age. The coronary arteries become constricted or blocked by atheromas - bulging masses or "plaques" that form within the walls lining the arteries.

"Atheroma" is the Italian word for porridge, because it resembles porridge when viewed under a microscope. It contains a mix of cholesterol-filled cells, inflammatory cells, and fibrous scar tissue.

Atherosclerosis is the term used to describe the gradual build-up and hardening of atheromas within the arterial walls. It is commonly referred to as "hardening of the arteries."

It can occur in any artery of the body and depending on the artery affected, specific symptoms can be expected. When the coronary arteries are affected then angina or a heart attack may occur, if the carotid arteries in the neck (they supply blood to the brain) are affected then a stroke may occur.

In almost all cases, the underlying cause of angina is the critical narrowing of one or more of the coronary arteries that supply blood to the heart.

The more atheromas that line the coronary arteries, the narrower the pathway for blood. Atherosclerosis often restricts as much as 70% of the blood that flows through the coronary arteries. Although the heart muscle receives enough blood for routine activities like walking or sitting, myocardial ischemia (insufficient blood in the heart muscle) results when the narrow arteries do not allow enough blood to reach the heart during periods of physical or emotional stress. This lack of blood will trigger an episode of angina.

If the flow of blood is blocked completely, a heart attack, which is damage to the heart muscle, can result.

A number of things contribute to coronary artery disease, but these factors are particularly important:

  • Family history
  • Smoking
  • Diabetes
  • Hypertension (high blood pressure)
  • Sedentary lifestyle
  • Elevated cholesterol (a fat-like substance needed for the development of body cells that is both produced in the body and found in animal foods; if levels of cholesterol in the body are too high, it can be deposited on artery walls)
  • Overweight or obesity

Someone with coronary artery disease may have one or more of these risk factors, but some people with the disease have none of the risk factors.

How Is Coronary Artery Disease Diagnosed?

The classic symptoms of heart disease include:

  • Chest discomfort that gets worse with activity and improves with rest (or with nitroglycerin pills)
  • Shortness of breath
  • Dizziness
  • Ankle swelling
  • Fainting

However, many people with coronary artery disease have no symptoms. Their heart disease may be diagnosed during a routine physical examination.

If a physician suspects heart disease, one or more tests may help to find out if there is disease and how serious it is.

Tests for coronary artery disease include:

  • An echocardiogram, which is a non invasive test that uses sound waves, taking pictures of how the walls of the heart move, allowing the doctor to see if they move abnormally.
  • An exercise treadmill test, also known as a stress test. While you walk on a treadmill, the physician monitors the electrical signal from your heart, which is recorded as an electrocardiogram (ECG). Changes in the ECG, which can indicate whether the heart is receiving adequate blood, while you exercise, can help the doctor to make a more accurate diagnosis. An echocardiogram or specialized nuclear scanning devices may also be used.
  • The stress thallium test. At the end of the regular stress test, a small amount of a safe drug is injected into your veins. This allows the physician to view the heart with a special scanning device and see which parts of the heart may not be getting enough blood.
  • A coronary angiogram (or arteriogram). In this test, the doctor injects a small amount of dye into an artery, and makes a video of the heart as the dye moves through. This shows exactly where thecoronary arteries might be blocked, and how big the blockages are.

Facts About Cardiac Bypass Surgery

Over 61 million Americans have some form of cardiovascular disease. Of these, over 29 million are men, over 32 million are women, and over 24 million are older than 65 years of age.

Coronary artery disease accounts for nearly three-quarters of all deaths from cardiovascular disease.

It is estimated that 571,000 cardiac bypass surgeries are performed on 355,000 people annually in the USA.

Of the people who undergo bypass surgery, 238,000 are men, 117,000 are women, and 27,000 are over 65 years of age.

For further information about angina and the treatment of coronary artery disease, go to Angina.

For further information about lowering your cholesterol, go to Lowering Your Cholesterol.

For further information about reducing the risk of heart disease, go toHow To Reduce Your Risk For Heart Disease.

Cardiac Bypass Surgery