Off-Pump Bypass Surgery Summary
In many ways, off-pump bypass (or OP-CABG) is similar to conventional bypass surgery. The main difference lies in the fact that a heart-lung machine is not used to employ cardiopulmonary bypass during the operation.
How does this differ from the conventional bypass operation?
- CPB is not normally employed
- heart-lung machine is not used
- the beating heart cannot be stopped
- the aorta cannot be clamped
- patient is not fully heparinized
- surgical connection of the graft to coronary artery is more difficult, since the heart is constantly moving
Why are some surgeons making things so tough on themselves?
The one minor drawback to using the heart-lung machine is that artificial circulation may cause injury to the blood cells and some organ systems of the body. While this may seem to be a detriment to the patient, it is important to consider ALL the benefits and disadvantages of off-pump bypass.
Possible Advantages to Off-Pump Bypass:
- Patients may recover more quickly from off-pump surgery thereby shortening hospital stay.
- Post-operative neurologic deficiencies may be reduced with off-pump techniques.
- Blood is not damaged by the “non-biological” surface of the tubes that lead from the patient to the heart-lung machine. The effect on the patient is a “whole body inflammation” response that can be minimized but not totally eliminated with conventional bypass techniques.
- Off-Pump bypass provides a more “physiologic” state for the patient when compared with conventional bypass.
- Off-pump bypass may offer a better renal protection when compared with conventional bypass.
- Extremely sick patients that may not be able to survive conventional CPB may be able to survive off-pump bypass.
Possible Disadvantages to Off-Pump Bypass:
- Surgical connection (anastomosis) of the graft to coronary artery is more difficult, since the heart is constantly moving.
- Patients may “crash” while procedure is being performed and CPB may not be able to be instituted quickly enough to save patients life. This in particularly a concern is perfusion is not already setup in the room. (Note: Emergency institution of CPB may be required on as many as 25% of all OP-CABG procedures)
- The distal anastomosis preformed may not be as good as one preformed on a quiet, non-beating heart. This may lead to increased platelet deposition at the anastomosis site and faster reocclusion of the bypass graft.
- Due to the increased difficultly of working on a beating heart, the surgeon may be reluctant to perform as many bypass grafts as they would perform with conventional bypass surgery.
- Off-Pump bypass may increase the overall surgical cost due to the expensive myocardial stabilization devices ($895 per case) and intra-vascular shunts that are required for the operation.
- There is a steep learning curve associated with performing off-pump bypass surgery, and many surgeons may perform the procedure without experience. This can result in worse outcomes or grave consequences.
- There are no long term studies available which conclusively prove any of the benefits describe above.
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.
