Coronary artery bypass (idea)

In Brief

A coronary bypass graft is a surgery used to treat coronary artery disease (CAD). It involves removing a section of artery or vein from elsewhere in the body and sewing it between the aorta and a location in the coronary artery to bypass a damaged or blocked section. This allows blood to flow normally again past the blockage and nourish the heart muscle so it can continue to function properly. If left untreated, coronary artery disease can result in angina pectoris (chest pain) and myocardial infarction (heart attack). Double, triple, and quadruple bypass surgeries refer to the number of blockages that must be bypassed.

Coronary Artery Disease (CAD)

Coronary artery disease is the most common form of heart disease, affecting almost 1.3 million Americans. It is characterized by restricted blood flow in the coronary arteries due to damage or blockage by plaque. Since the coronary arteries supply blood to the heart, restricted blood flow through them can be extremely serious. Symptoms can include angina pectoris (Latin for "strangling in the chest"), which can be very painful, and myocardial infarction (commonly known as a heart attack), both due to lack of oxygen to the heart muscle. Risk factors include include being male, high blood cholesterol, diabetes mellitus, hypertension (high blood pressure), and cigarette smoking.

The heart is constantly working. 24 hours a day, every day of your life, your heart works tirelessly to pump blood through your body and supply oxygen, nutrients, and antibodies to all the various cells and organs in your body. In order to fuel this massive effort it requires a constant and significant supply of blood itself, because its walls are too thick to absorb what it needs from the blood inside of it. If this critical supply is restricted, the heart cannot do its job and literally begins to die. Considering the critical importance of the heart, measures must be taken to correct this condition.

Before doing anything too hasty though, the coronary artery disease must be confirmed. This can be done by cardiac catheterization, which can measure blood pressure within the heart and how much oxygen is in the blood, as well as providing information about the pumping ability of the heart muscle. Alternately a noninvasive stress test can be performed by electrocardiogram monitoring while the patient is running on a treadmill.

In some cases, the condition can be treated with a minor operation. One such option is an angioplasty, in which a small balloon is inserted into the blockage in the artery and inflated. This pushes the plaque to the walls of the artery, opening it back up. Other times prescription drugs such as nitroglycerin can be used to dilate the blood vessles so blood can flow more easily past the blockage. These techniques are not effective against serious, numerous, or recurring blockages, however, so about 10% of CAD patients require a more serious and invasive surgery.

Coronary Artery Bypass Graft (CABG)

Also called coronary artery bypass surgery, coronary bypass surgery, heart bypass surgery, bypass surgery, and double, triple, or quadruple bypass surgery (depending on the number of blockages to be bypassed). They all refer to the same technique.
IWhoSawTheFace informs me that quintuple bypass surgeries are also performed regularly. David Letterman and Boris Yeltsin have both undergone this procedure.

Coronary bypass surgery is one of the most common major operations in the United States, and the most common heart surgery in the United States. About 350,000 of them are performed in the U.S. every year. By comparison, there are about 2,000 heart transplants performed annually, partially due to a lack of donors. This large number of procedures has given medical science a huge amount of information about how to make the surgery safer and recovery faster. Patients over 80 years old have been treated successfully and the mortality rate is between 1 and 2%.

The technique was developed by Argentinean cardiologist René Favaloro (1923-2000) in 1967 using the great sapheneous vein in the leg. These days the left internal thoracic artery is preferred, as the artery is already near the heart and is stronger and longer-lasting than a vein. A successful graft can last 10–15 years.

Before Surgery

The day before surgery, the patient is required to bathe in order to remove dirt and germs from the body to help minimize the risk of infection. The chest area may be shaved if necessary. The patient should not eat the night before surgery, because anaesthesia is safest on an empty stomach. The patient should not smoke two weeks before surgery because of blood clotting and breathing problems.
Ouroboros says the effects of smoking on the body are so pronounced, the surgeon operating on his father's coronary bypass could tell he had smoked in the past week by touching the lungs.

Any medications, allergies, cold or flu symptoms, health problems, or other things which may complicate the procedure or recovery should be reported to the doctor before surgery. Since an anticoagulant will be used during surgery, they also need to know if the patient has taken aspirin or other blood thinners recently.

In order to get a complete picture of the health and status of the patient, a battery of tests will be run. Electrocardiogram, blood test, and urine test provide a general health update; and a dye which shows up on X-ray film will be injected into the coronary arteries to provide a map of the area.

Immediately before surgery, the patient will be washed again and scrubbed with antiseptic in the surgery area to further reduce the risk of infection. A mild tranquilizer will be administered to help the patient relax. Electrodes attached to the chest will provide a constant update of the heart's activity to an electrocardiogram.

Next, a local anesthetic will numb an area in the patient's arm for the insertion of an IV to administer the general anesthetic. Soon, the patient will be asleep and unable to feel or remember anything during the operation.

The last step before surgery begins is the insertion of two tubes down the throat and another up the urethra. A tube down the trachea will take over the breathing functions through a respirator machine. A second tube down the esophagus (via the nose) will prevent liquid and air from collecting in the stomach. The urethra catheter allows urine to drain during the operation.

Surgery

Surgery begins with a procedure called a median sternotomy, which is an incision down the sternum (breastbone), to crack open the chest. A sternal retractor is then put in place to hold the chest open during the operation. This exposes the heart in the chest cavity.

In most bypass surgeries, the heart must be stopped and bypassed so that the operation can proceed. A device called a cardiopulmonary bypass (heart-lung pump), which takes over for the operation of the heart and lungs, is used for this. The pump extracts blood from the right atrium of the heart into a reservoir called an oxygenator, which bubbles oxygen up through the blood to enrich the hemoglobin in the red blood cells. The blood then passes through a filter to remove any lingering air bubbles and is pumped directly into the aorta, from where it enters the rest of the body.

Once the heart-lung pump is hooked up, the heart is stopped and cooled. Cooling the heart keeps it safe from tissue damage for 2 to 4 hours during the surgery by reducing its need for oxygen. The surgery can actually take between 2 to 6 hours depending on the number of bypasses that are required. The heart can be cooled either by cooling the blood in the heart-lung pump, or by pouring a cold saline solution over it. Additionally, an injection of a potassium solution can speed up the process of stopping the heart.

If the surgery is relatively minor, it may be possible to perform "off-pump" (without the heart-lung pump) by holding the heart in place with a suction stabilizing device. This can make recovery quicker and easier.

The final procedure before beginning the graft is to obtain a length of artery or vein which will be used to bypass the blockage. If a vein, such as the leg's great sapheneous vein, is used, the valves will either have to be removed or the vein will need to be oriented in the correct direction so the valves do not stop the blood flow. Otherwise, an artery such as the left internal thoracic artery or radial artery from the arm may be used. Arteries are thicker and more robust, and tend to last longer when used for the bypass.

The left internal thoracic artery has the additional advantage of being in a convenient location near the heart and already attached to the aorta so only one graft will need to be made, past the blockage. Otherwise a section of vein or artery will be removed from its original position to be grafted between the aorta and a point past the blockage in the coronary artery. For multiple bypasses, multiple veins and arteries may be used.

When the grafting is complete, the new sections of blood vessel between the aorta and the coronary artery have formed a new route which blood will use to bypass the blocked area or areas of the coronary artery. Normal blood flow capacity will have been restored and the heart can get back to work as soon as the heart-lung machine is disconnected and it is warmed back up.

After Surgery

Cracking the chest open and operating on the heart isn't exactly outpatient surgery. A massive amount of damage has been done to the body by the surgical procedure which will take time and professional care to heal, and leaving the chest cavity open for so long carries a risk of infection. Generally the patient will stay in the hospital for about a week for observation, including one to three days in the intensive care unit (ICU). The chest incision will usually stop bothering the patient after 48 to 72 hours, but patient will generally feel washed out or drained for most of the recovery period while the body heals itself.

Of course, changes in diet and lifestyle after the surgery can go a long way toward avoiding a repeat performance. Limiting fat and cholesterol can help prevent more blockages, because that's what they're mostly made of. Quitting smoking has more health benefits than can be listed here and should absolutely be part of the recovery process. Exercise such as walking and swimming can help normal strength return, and the doctor may recommend joining a cardiac rehabilitation program. Managing stress will also help keep a heart healthy by controlling blood pressure and other benefits.

An office job or other work which doesn't involve a lot of heavy lifting can usually be restarted in 4 to 6 weeks. Other jobs may need to wait longer. In certain cases the doctor may recommend finding a less physically demanding job.

With these precautions, a typical bypass surgery will last about ten to fifteen years. Roughly a quarter of bypass patients will need a second operation within ten years. Learning how to take care of yourself is a big part of making it last as long as possible.

What If it Didn't Work?

In rare cases, the coronary artery bypass graft will not take or will not be effective enough to eliminate the symptoms of coronary artery disease. There are other techniques which can be used.

Percutaneous transmyocardial revascularization (PTMR) and transmyocardial laser revascularization (TMLR) are two techniques which use lasers to increase blood flow to critical areas of the heart. Laser energy during a PTMR is delivered through a fiber optic catheter, and TMLR is done through a small chest incision. The lasers are used to punch several holes in the heart muscle wall, which then become new channels through which blood can flow. This allows blood to reach areas of the heart previously obstructed by the blockages in or damage to the coronary arteries, and have shown promise in cases where medicine, angioplasty, and bypass surgery are not effective.

Terminology

Anaesthesia

a medicine given before surgery to numb the pain of the procedure. Local anesthetic numbs a small area where it is applied, and general anesthetic renders the patient completely unconscious.

Anticoagulant

a medicine given to prevent the blood from thickening in order to allow it to flow more easily.

Coronary

resembling, or situated like, a crown or circlet.

Artery

a type of blood vessel which supplies oxygenated blood to the body. Arteries tend to be thicker and stronger than veins because they are under greater pressure.

Vein

a type of blood vessel which returns deoxygenated blood to the heart. Unlike arteries, veins have valves to prevent backflow.

Coronary artery

one of the blood vessels circling the heart muscle that supplies it with blood. There are three major coronary arteries. The left coronary artery is the more important one, as it supplies blood to the left ventricle of the heart, which does the heaviest pumping. The left coronary artery branches into two smaller arteries, the left anterior descending artery and the circumflex artery. A blockage in the left anterior descending artery is called the "widow maker".

Coronary artery disease

the most common form of heart disease, caused by a buildup of plaque in the coronary arteries. CAD can be fatal.

Electrocardiogram

monitoring of the electrical activity of the heart to evaluate its condition and regularity of its beat via electrodes placed on the body.

Graft

a method of attaching one piece of biological tissue to another so that they heal to each other.

Plaque

a buildup of cholesterol, fatty compounds, calcium, and fibrin (blood-clotting material) in the arteries which can cause a blockage and restricted blood flow.

For borgo. We all wish you a quick recovery.

Sources:
http://www.usatoday.com/news/nation/2004-09-03-bypass-szabo_x.htm
http://heart.healthcentersonline.com/bypasssurgery/bypasssurgery.cfm
http://en.wikipedia.org/wiki/Coronary_artery_bypass_surgery
http://www.tmc.edu/thi/cab.html
http://www.medem.com/medlb/article_detaillb.cfm?article_ID=ZZZFFEJNKTD&sub_cat=569
http://www.sts.org/sections/patientinformation/adultcardiacsurgery/cabg/index.html
http://www.tmc.edu/thi/cad.html