Heart bypass surgery

Alternative names   

Bypass surgery - heart; CABG; Coronary artery bypass graft

Definition   

This surgery is done to bypass clogged arteries supplying the heart.

Description   

Coronary arteries are the small blood vessels that supply the heart muscle with oxygen and nutrients. Fats and cholesterol can accumulate inside these small arteries, and the arteries can gradually become clogged. This buildup of fat and cholesterol plaque is called atherosclerosis.

When one or more of the coronary arteries becomes partially or totally blocked, the heart does not get an adequate blood supply. This is called ischemic heart disease or coronary artery disease (CAD). It can cause chest pain (angina).

Sometimes CAD does not cause pain until the blood supply to the heart becomes critically low, and the muscle begins to die. The first symptom of CAD in this case may be a potentially deadly heart attack. Symptomless CAD is especially common in diabetics.

Overview of the procedure

Heart bypass surgery creates a detour or "bypass" around the blocked part of a coronary artery to restore the blood supply to the heart muscle. The surgery is commonly called Coronary Artery Bypass Graft, or CABG (pronounced "cabbage").

After the patient is anesthetized and completely free from pain, the heart surgeon makes an incision in the middle of the chest and separates the breastbone.

Through this incision, the surgeon can see the heart and aorta (the main blood vessel leading from the heart to the rest of the body). After surgery, the breastbone will be rejoined with wire and the incision will be sewn closed.

Artery and vein grafts

If a vein from the leg, called the saphenous vein, is to be used for the bypass, an incision is made in the leg and the vein removed. The vein is located on the inside of the leg, running from the ankle to the groin. The saphenous vein normally does only about 10% of the work of circulating blood from the leg back to the heart. Therefore, it can be taken out without harming the patient or harming the leg.

It is common for the leg to swell slightly during recovery from the surgery, but this is only temporary and is treated by elevating the leg.
The internal mammary artery (IMA) can also be used as the graft. This has the advantage of staying open for many more years than the vein grafts, but there are some situations in which it cannot be used.

The left IMA, or LIMA, is an artery that runs next to the sternum on the inside of the chest wall. It can be disconnected from the chest wall without affecting the blood supply to the chest. It is commonly connected to the artery on the heart that supplies most of the muscle, the left anterior descending artery, or LAD.

Other arteries are also now being used in bypass surgery. The most common of these is the radial artery. This is one of the two arteries that supply the hand with blood. It can usually be removed from the arm without any impairment of blood supply to the hand.

Traditional approach

In the traditional surgery, the patient is connected to the heart-lung machine, or bypass pump, which adds oxygen to the blood and circulates blood to other parts of the body during the surgery. This is necessary because the heart muscle must be stopped before the graft can be done.

One end of the graft is stitched to an opening below the blockage in the coronary artery. If the grafted vessel is the saphenous vein or the radial artery, its other end is stitched to an opening made in the aorta. If the grafted vessel is the mammary artery, its other end is already connected to the aorta.

The entire surgery can take 4-6 hours. After the surgery, the patient is taken to the Intensive Care Unit. For a few days after the surgery, the patient is connected to monitors and tubes.

Other techniques

Other surgical techniques for this procedure are being used more frequently. One popular method is to avoid the use of the heart-lung machine. This is called off-pump coronary artery bypass or OPCAB. This operation allows the bypass to be created while the heart is still beating.

The advantage here is that use of the heart-lung machine can lead to some loss of memory and mental clarity, while with OPCAB, that risk is reduced because the heart isn't stopped, and the blood isn't oxygenated externally.

Another alternative is the use of smaller incisions that avoid splitting the breastbone. This is referred to as Minimally Invasive Direct Coronary Artery Bypass or MIDCAB.

Coronary bypass surgery can now be performed with the aid of a robot, which allows the surgeon to perform the operation without even being in the same room as the patient.

Indications   

Coronary artery bypass surgery is a treatment option for ischemic heart disease (too little blood reaching the heart muscle). Coronary surgery is recommended when there is disease of the left main coronary artery, disease of three or more vessels (triple vessel disease), or nonsurgical management hasn't worked. Nonsurgical management includes medication and/or angioplasty.

The earliest symptoms of ischemic heart disease include angina (chest pain) and shortness of breath. A person may have no symptoms; have mild, intermittent chest pain; or have more pronounced and steady pain. Still others have CAD that is severe enough to make everyday activities difficult.

Symptoms that usually bring a person to a doctor are a feeling of heaviness, tightness, pain, burning, pressure, or squeezing. This is usually behind the breastbone, but sometimes it is also in the arms, neck, or jaw. Some people have heart attacks without ever having any of these symptoms first.

In cases where there are no symptoms, a doctor may suspect CAD and perform a stress test to determine if it is present. CAD is sometimes suspected if there is a family history of heart disease and a combination of other factors, including high blood cholesterol, diabetes, high blood pressure, cigarette smoking, and being male.

Because CAD varies so much from one person to another, the way it is diagnosed and treated will also vary. Heart bypass surgery is just one treatment.

Risks   

When considering the risks of CABG, it is important to remember that bypass surgery has been performed for more than 30 years. Cardiovascular surgeons have received extensive training in bypass techniques.

It is the most frequently performed major surgery in the United States, with over a half million done each year. As with any surgery, the health of the patient prior to surgery is a major consideration in determining risks.

Health conditions that should be considered prior to surgery are:

• Age -- patients over 70 are at a slightly higher risk for complications
• Gender -- women have a slightly higher risk
• Previous heart surgery -- puts a person at a higher risk
• Having another serious medical condition (such as diabetes, peripheral vascular disease, kidney disease, or lung disease)

Possible risks in having CABG are:

• Heart attack, which occurs in 5% of these surgeries
• Stroke, which occurs in 5% of these surgeries (the risk is greatest in those over 70)
• Blood clots
• Death, which occurs in 1 - 2% of those who have the surgery (that means 95 - 98% have no serious complications)
• Sternal wound infection, which occurs in 1 - 4% of these surgeries (this complication is most often associated with obesity, diabetes, or having had previous CABG)

In about 30% of patients, "post-pericardiotomy syndrome" can occur anywhere from a few days to 6 months after surgery. The symptoms of this syndrome are fever and chest pain. It can be treated with medication.

The incision in the chest or the graft site (if the graft was from the leg or arm) can be itchy, sore, numb, or bruised.

Some people report memory loss and loss of mental clarity or "fuzzy thinking" following CABG.

As with all surgeries, there is a risk for heavy bleeding. In case a transfusion is needed during or after surgery, ask your doctor about making arrangements for an "autologous" pre-operative blood donation (banking your own blood for surgery).

You may also have family or friends with a compatible blood type donate blood for your surgery. The hospital, Red Cross, or local blood bank can provide family members and friends with necessary information about blood donation for your surgery.

There are general risks from anesthesia. These include reactions to medications and problems breathing.

Expectations after surgery   

Every year over one half million Americans have coronary bypass surgery to relieve symptoms and prolong their lives. In the majority of people who have the surgery, the grafts remain open and functioning for 10 to 15 years.

CABG will improve blood flow to the heart but NOT prevent the eventual recurrence of coronary blockage. Lifestyle changes are necessary -- such as not smoking, improved diet, regular exercise, and treating high blood pressure and high cholesterol.

Convalescence   

After the operation, the patient will spend 5 - 7 days in the hospital, with the first 2 hours in an intensive-care unit (ICU). In the ICU, heart function is monitored continuously.

Patients may require the temporary assistance of a breathing tube for a few hours after surgery. Two to three tubes in the chest drain fluid from around the heart and are usually removed one to three days after surgery.

A urinary catheter in the bladder drains urine until the patient is able to void on his own. Intravenous lines (IV) provide fluids and medications. Nurses watch the monitors and check vital signs (pulse, temperature, breathing) constantly.

When constant monitoring is no longer needed, usually within 12 - 24 hours, the patient is moved to a regular or a transitional care unit. Activity is gradually resumed and the patient may begin a cardiac rehabilitation program within a few days. The incision in the chest does not bother most people after the first 48 - 72 hours.

After surgery, it takes 4 - 6 weeks to start feeling better. During recovery it is normal to:

• Have a poor appetite -- it will take several weeks for it to return.
• Have swelling in the leg if the graft was taken from the leg. Elevating the leg and wearing elastic TED hose for several weeks helps reduce swelling.
• Have difficulty sleeping at night -- this will improve.
• Have constipation.
• Have mood swings and feel depressed -- this will get better.
• Have difficulty with short-term memory or feel confused -- this also improves.

The full benefits from the operation may not be determined until 3 - 6 months after surgery. Sexual activities may be resumed 4 weeks after surgery. All activities that do not cause fatigue are permitted, and the schedule for resuming normal activities is determined with the physician.

Update Date: 5/30/2006

Updated by: J.A. Lee, M.D., Division of Surgery, UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network.