Off Pump CABG

Dateline: 01/25/98

Over the past month, we have discussed the concept of minimally invasive heart surgery, and the use of this novel technique in treating coronary artery disease , heart valve disease and birth defects of the heart. This week, we will discuss one of the types of coronary bypass - Off Pump CABG.

For more information on minimally invasive surgery, including coronary bypass operations, you can visit the MICAS website.

Off-Pump CABG - What is it ?

In many ways, off-pump CABG is similar to conventional CABG. The difference lies in the fact that the patient is NOT hooked on to the heart-lung machine.

How does this differ from the conventional operation done using the machine ?

Without using the heart-lung machine

• the heart-beat cannot be stopped
• the aorta cannot be clamped
• cardioplegia cannot be injected
• surgical connection of the graft to coronary artery is slightly more difficult, since the heart is constantly moving

But then why are surgeons making things so tough on themselves ?

Because all the harmful effects of using a heart-lung machine are avoided by off-pump CABG. If there is one major drawback to using the heart-lung machine, it is this - the artificial circulation causes injury to the blood cells and all organ systems of the body. The damage occurs because

• the "non-biological" surface of the tubes that lead from the patient to the machine can injure blood cells
• blood circulating inside these tubes is subject to considerable external stress forces
• air, plastic particles and tiny blood clots might get mixed in the blood stream and cause damage to different organs

The effect on the patient is a "whole body inflammation" response that can be minimized but not totally eliminated by current perfusion techniques.

Off-Pump CABG - How is it done ?

The surgeon opens the chest by a vertical midline incision splitting the breast bone (sternum). Some surgeons place sutures in preparation for connection to the heart-lung machine, to allow immediate establishment of an artificial circulation in case of accidents during surgery. A few others do not make any such preparation in advance. CABG is performed to the diseased coronary arteries in the conventional manner, using either vein or artery (ITA) grafts. To make the process easier, the heart may be transiently slowed down using drugs like Esmolol or Adenosine. The surgeon takes care to avoid excessive manipulation or compression of the heart during the operation. Most diseased coronary arteries can be safely accessed and grafted using this method. In the event of difficulty or complications, the operation is completed in the standard fashion after hooking the patient on the heart-lung machine.

For more information on minimally invasive surgery, including coronary bypass operations, you can visit the MICAS website.