Minimally Invasive Direct Coronary Artery Bypass (MIDCAB)

MIDCAB procedures are coronary artery bypass operations done without the aid of a heart-lung machine and that use novel devices and techniques. Coronary bypass surgery has been performed by some surgeons without the use of the heart-lung machine since the beginning, but the vast majority has used, and still use, the heart-lung machine.

New technology, however, has prompted many heart surgeons to take a long, hard look at performing coronary bypass grafts in selected patients without the use of the heart-lung machine. Some surgeons now are performing surgery, particularly when only one or two bypasses are needed, through a small incision in either the left or right side of the chest, depending on where the bypass graft is to be placed. This is done without the use of the heart-lung machine. There are certain advantages to performing the surgery without the aid of the heart-lung machine, yet there are many advantages to performing heart surgery with the heart-lung machine. Nonetheless, these techniques are being evaluated at many centers around the world.

If everything goes well and the heart lung machine is not used, you can have the breathing tube removed sooner after the surgery and may be able to go home a day or two earlier. Some of the surgeons doing the surgery without a heart lung machine have used videoscopes with remote TV cameras to perform portions of the operation, such as freeing up the internal mammary artery. Some have used videoscopes with special instruments to join the coronary artery to the internal mammary artery. Some surgeons use the routine midline incision through the breastbone but then perform the coronary bypass procedure without the heart lung machine. Again, there are advantages and disadvantages to doing this. Not all patients undergoing heart surgery at this time are eligible for these MIDCAB procedures.

Starting in 1995, few surgeons began performing coronary artery bypass grafting (CABG) through a three-inch incision between the ribs on the left side of the breast bone. The procedure was performed on a beating heart rather than on a stopped heart, and the minimally invasive direct coronary artery bypass (MIDCAB), or “keyhole” form of cardiac surgery, was born. The “direct” in the acronym means that although the bypass was performed through a small incision, it was done while viewing the heart directly rather than with a scope.

This form of surgery has two benefits for postoperative recovery: Patients do not undergo as much discomfort as a large incision would cause, and the heart lung machine, which can contribute to the undesirable side effects of heart surgery, is not used.

At first, the MIDCAB operation was basically limited to a single bypass on the front surface of the heart and, because the heart was still moving, the connection of the bypass was technically challenging, and the results of the procedure were appropriately questioned. This issue was largely solved by the introduction of “stabilizers,” which are mechanical feet placed against the surface of the heart. This produces a local area of "non moving heart" and allows for precise sewing while the remainder of the heart continues to beat and support the circulation.

In 1995, the Port-Access device was introduced which allows the surgeon access to the heart through a smaller incision while still using the heart lung machine. It allows not only CABG operations but also surgery on the mitral valve inside the heart. Both are performed through a three-inch incision on either the left (CABG) or right (mitral valve) side of the sternum. In addition to the ability to use the heart lung machine without opening the chest, this procedure offers the ability to safely stop the heart with a balloon catheter placed in the aorta just above the heart.

Currently, most of the focus in the field of minimally invasive cardiac surgery is on the off-pump coronary artery bypass (OPCAB) procedure. In the OPCAB operation, multiple coronary arteries can be bypassed. Although the breastbone is still divided, the heart-lung machine is not utilized, and newer generation stabilizers are used to immobilize each artery to be bypassed in turn while the heart continues to beat.

The field of minimally invasive cardiac surgery and its role in managing heart disease will require further comparison, not only with conventional bypass surgery, but also with the “least invasive” form of coronary bypass, percutaneous transluminal coronary angioplasty (PTCA).