#5 - Coronary Artery Bypass Grafting
October 31, 2002
By Audrey Walton, MedTech1 Staff
Performed over 200,000 times a year in the United States alone, Coronary Artery Bypass Surgery, also known as Coronary Artery Bypass Grafting or CABG, is the most common surgical procedure in the country. Dr. Michael Lysaght, a professor of engineering and medicine at Brown University, calls CABG "the gold standard in heart surgery," commenting that "conventional CABG has been around for the past four decades, and in that time it has nearly been perfected." Worldwide, over 1 million bypass surgeries are performed every year, with a 99% success rate. "Heart attack remains the most common cause of death in the U.S.," says Dr. Christian T. Campos, Associate Professor of Surgery at UMass Memorial Hospital in Boston, and President of the American Heart Association’s Metro-Boston Board. In fact, coronary artery disease is currently the single greatest cause of death in the United States, causing more than 900,000 deaths every year. "It was common even in the 1950s. But in the 1950s and 1960s, when people had heart attacks, the standard treatment was to hospitalize and rehabilitate them; so, for example, when Eisenhower had a heart attack, he was hospitalized for three months even during his term as President. In the mid 1950s, the idea came: ‘Why don’t we replaced these blocked arteries with something?’ In the sixties, seventies, and eighties, bypass surgery rapidly became one of the most common operations in the United States."
Although there are currently alternative means to treat these blockages, CABG remains a common and often crucial procedure, and has saved millions of lives since its inception. The goal of bypass surgery is to bypass the blockage by suturing a vein (most commonly from the patient’s leg) to the blocked artery, thereby restoring the flow of blood to the heart. "Bypass surgery was an incredibly important development," says Dr. Campos. "Looking back not even forty years ago, the only treatment for heart attack or cardiac disease was [to tell patients], ‘Don’t be so active.’ I think the development has really revolutionized the care of patients with heart disease. It can prolong [people’s] lives significantly."
Conventional CABG is a major operation, in which the surgical team takes a graft from another vein in the patient’s body, then splits open the breast bone, or sternum, with a surgical tool resembling a jigsaw. Most commonly, the surgical team makes an incision in the pericardium, the membrane which surrounds the heart, and removes a segment of either the Internal Mammary Artery or the Greater Saphenous Vein, a long straight vein which runs from inside the ankle bone to the groin, to use as a bypass graft.
In conventional CABG, the patient is put on an artificial circulation system known as a heart-lung machine. The coronary arteries are typically suffused with a potassium solution, which causes the heart to cool, relax, and stop beating. When the surgery is completed, the effects of this solution are chemically reversed. While this life-saving procedure has been nearly perfected over the last four decades, traditional CABG remains a painful and sometimes traumatic procedure for the patient. The heart-lung machine has been associated with an increase in blood transfusions, kidney and lung complications, a greater risk of stroke, and longer hospital stays.
Recent surgical advances have given rise to beating heart or "off-pump" bypass surgery, in which the heart continues to beat even during the operation and no heart-lung machine is used. Individuals who once had a high risk of complications, in particular people with diabetes, with a history of stroke, and with poor overall health, can now undergo bypass surgery much more safely.
The two primary forms of off-pump bypass surgery are OPCAB, short for "off-pump coronary artery bypass," and MIDCAB, short for "minimally invasive direct coronary artery bypass." As of 2000, MIDCAB had a 90% effectiveness rate in worldwide studies. OPCAB has also been shown to result in quicker recovery times, shorter hospital stays, less blood trauma, and fewer cognitive and neurological risks than conventional bypass surgery. For a detailed comparison of MIDCAB and conventional CABG procedures, as well as photos and video of a MIDCAB operation, see the Brown University Medical School website. "Some particularly aggressive surgeons may be doing eighty to ninety percent of operations off-pump," says Dr. Campos. "Most people are doing about fifty-fifty. When this first came out, the equipment that was first used compared to what we have now, gosh, it was crude. I bet that a lot of surgeons who never do off-pump surgery are going to start, now that the technology is improved. I’m one of them. A year ago I didn’t do any of my patients off-pump. Now I probably do 20-30 percent off-pump. And I’d say that that number will probably increase to 50-50."
Last updated: 31-Oct-02