Coronary Artery Bypass Grafting - History and Technique
Dateline: 08/03/97
In this week's article, we take a closer look at one of the options for treating coronary artery disease - the bypass graft operation (CABG).
Down Memory Lane
The operations that were tried to treat coronary artery narrowing were ingenious, or even sometimes bizarre, and generally attempted to provide alternate sources of blood flow to the heart muscle. They ranged from tying up the opening of the coronary vein, or abrading the heart's surface and wrapping it up in chest wall muscle or omentum from the stomach, to the only operation which provided some durable benefit - the Vineberg operation. In this procedure, the internal mammary artery (which is a large artery on the inside of the chest wall) is disconnected and buried inside the muscle of the left ventricle using sutures.
The credit for the first experimental efforts to treat coronary narrowing by bypassing the diseased artery using alternative conduits goes to Rene Favoloro, Effler and their associates at the Cleveland Clinic Foundation. The FIRST human coronary bypass operation using vein from the patient's leg as a conduit was performed in 1962 by David C.Sabiston Jr. at Johns Hopkins hospital.
Dudley Johnson at Milwaukee was the first to report successful operations for disease in the left coronary artery, as early as in 1969 (301 patients with only 12% mortality, excellent results by the standards of that period).
In 1967, a little known Russian surgeon, Kolessov, who was chairman of surgery at the Leningrad Medical Institute, for the first time used the internal mammary artery as a conduit to graft a diseased left coronary artery. It was only as late as in 1988 that this great man's achievements became common knowledge worldwide. In the meantime, in 1968 at New York University, Green and Tice independently described the same technique, and the internal mammary artery is today one of the most commonly used conduits for CABG.
Over the past three decades, with the introduction of techniques like cardioplegia, improved instruments and suture materials and other technological advances, CABG has become the most commonly performed heart operation all over the world, with over 300,000 procedures carried out in the United States alone every year.
How is a CABG operation performed ?
The Principle:
What do you do when you come across a blocked highway ? Take a detour, of course. One which connects back to the highway beyond the area that is blocked. The CABG operation does the same on the "highway" of the blood stream. When a native coronary artery is obstructed, the CABG operation provides a detour by connecting the aorta on one end to the coronary artery beyond the area of obstruction - by interposing a tube or "conduit" which may be a piece of artery or vein or synthetic material.
The Technique:
CABG is an "open heart" operation - that is, one which is done with the patient hooked on to a artificial heart-lung machine while the heart is stopped and operated on. The conduit which is a portion of vein or artery from another part of the body is first prepared for use - or as we medics say, "harvested".
The diseased coronary artery is then identified and an opening made on it beyond the area
of obstruction. The surgeon, using magnifying loops that make the field of operation appear
thrice as large, then sutures the conduit (white arrow) to this opening on the coronary
artery using special thread that is as fine as a strand of hair, and tremendously strong. When you
consider that the average coronary artery is only around 3 millimeters in size, you will truly
appreciate the technical skill and delicacy needed to execute this complex operation.
The other end of the conduit is then sutured on to the aorta itself. The procedure is repeated on all the coronary artery branches that are significantly diseased.
This in brief is what a CABG operation is all about. There are numerous technical variations of this procedure which I will discuss in future articles. If you have any comments or suggestions about this article or any others as well, please e-mail me.
