Coronary artery bypass (CAB) surgery has been one of world's top operations for almost 40 years. More than 800,000 bypasses are done each year, including about 600,000 in the United States.
CAB's rite of passage from youth to middle-age has changed its popular image.
Once it looked like a daring, high-risk affair, best done by virtuoso surgeons in a few big medical centers.
Now people sometimes view CAB as a “routine” operation with little risk. Bypasses are done in communities almost everywhere, even on patients in their 80s and 90s. At many hospitals, the death rate is below 3 percent.
Despite its popular reputation as a fully perfected operation, CAB is causing what experts describe as “an epidemic” of side effects. That's the term Dr. Daniel B. Mark, of Duke University, used in a March Journal of the American Medical Association article.
The side effects involve minor brain damage in up to 80 percent of patients discharged after CAB surgery.
Symptoms include memory loss, confusion, and difficulty in performing regular daily activities. They often last for months.
Although many patients recover fully, some have lasting problems. One study checked patients five years after CAB. It found that 42 percent were still having memory problems, which doctors term “cognitive impairment.”
In the past, some doctors accepted the side effects as a small but unavoidable price to pay for CAB's benefits. Now, however, efforts are underway to re-invent the CAB so that it becomes a “brain-safe” operation.
CAB involves bypassing blockages in the coronary arteries with a vein removed from the patient's leg. The blockages form inside the arteries - like rust inside an iron pipe - from cholesterol and other material.
They reduce blood flow to the heart's pumping chambers, and are the main cause of heart attacks.
In the traditional bypass, doctors stop the patient's heart while sewing the vein from one side of the blockage to the other. A heart-lung machine pumps blood and supplies it with oxygen during the operation.
That machine is a prime suspect as the cause of brain damage. Experts think it may result in tiny clots that flow to the patient's brain, block blood vessels, and damage brain cells.
In an effort to make bypasses safer, surgeons are doing “beating-heart” or “off-pump” bypasses. The operations do not use a heart-lung machine. An estimated 20 percent of all CABs done today are off-pump operations. Experts say that figure will reach 50 percent by 2005.
Despite the growing popularity, experts don't know the benefits of off-pump CAB because few studies have been done.
One of the biggest compared off-pump and regular CAB in 248 patients in the Netherlands. It found that off-pump surgery had only small benefits in reducing brain injury.
Another suspect in involves deposits that break loose from the aorta, and travel to the brain. The aorta is a big artery carrying blood from the heart to the rest of the body. Surgeons clamp it during CAB.
Surgeons are combining off-pump CAB with other new techniques that avoid clamping of the aorta. Researchers also are focusing on another brain-injury suspect - a body-wide immune system response that may be triggered by open heart surgery.
Nobody should be blase about any surgery, especially an operation as major as CAB.
Patients and families usually ask a lot of questions before agreeing to surgery. They involve the benefits and possible complications of surgery; alternative treatments; the surgeon's track record, and number of operations done at the hospital each year.
Reducing the risk of brain injury definitely is one of the topics that CAB patients and family members should discuss with the doctor.
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