Coronary artery bypass grafting (CABG) is the most commonly performed procedure by MASA surgeons. In the year 2000 alone, MASA surgeons performed 1,675 CABG operations, 53 reoperative CABG operations, and 232 combined CABG and valve operations. Nationwide, 150,000 CABG operations were performed in 1999, making CABGs one of the most commonly performed operations in the country.
When atherosclerosis develops in the coronary arteries, flow of blood through these vessels is blocked, and the blood supply to heart muscle is jeopardized. If the blockages are significant enough, the end result will be a heart attack or sudden death. CABG is an operation that is designed to re-route the blood around these blockages to prevent a heart attack or sudden death. Conventionally an artery from behind the breast bone, and veins from the legs are used to “bypass” the blood around the coronary artery blockages.
The operation takes 2-3 hours to perform, and begins after general anesthesia is induced. Patients are completely asleep during the entire course of the operation. Physician assistants remove saphenous vein through incisions in the legs. The length of the incision is dependent upon the amount of vein required to complete the necessary number of “bypasses” (ie 5 bypasses will require more vein than 2 bypasses). There are many “redundant” veins in the leg … once some vein is removed, the other veins in the leg take over for the missing vein. Once the vein has been removed from the leg, it has the appearance of a long tube or “conduit”. The vein will be divided into separate shorter segments, each of which will be used for individual bypasses.
As vein is removed from the leg by a physician assistant, the surgeon simultaneously opens the chest by dividing the breast bone or sternum, affording excellent exposure of the heart (see Figure 1). An artery behind the sternum, the left internal mammary artery (LIMA) is taken down and one end prepared for bypass grafting. Tubes or cannulae are inserted into the heart and major blood vessels surrounding the heart in preparation for cardiopulmonary bypass with the heart-lung machine.
At this point, the patient is placed on the heart-lung machine. Blood is re-directed from the heart into the heart-lung machine. This permits the surgeon to safely operate on the heart without blood pumping through it. The heart is then stopped, and the heart-lung machine continues to pump freshly oxygenated blood to the rest of the body, in effect, taking over the roles of the heart and lungs.
The diseased coronary arteries are now identified and opened beyond the level of the blockages. The open ends of the saphenous veins and LIMA are now sewn to the openings in the coronary arteries using very fine non-absorbable suture material, these are called the “distal” anastamoses. Surgeons wear special magnifying lenses in order to see the delicate suture and small vessels.
Because the “inflow” through the LIMA is left intact, as soon as the LIMA anastamosis is completed, blood flow is established to that region of the heart. A vein graft however, is harvested as a “free graft” and has no “inflow” … therefore, after the “distal” vein graft anastamosis is constructed, the other end of the vein graft is sewn to the aorta (the main artery leaving the heart) in order to establish “inflow”. These are called the “proximal” anastamoses. After this stage, blood flow has now been established beyond all the blocked arteries, and the heart has effectively been “bypassed” (see Figure 2).
The heart-lung machine is then gradually weaned off, and the patient’s heart and lungs resume their normal functions. The cannulae are removed from in and around the heart, and the sternum and incisions are closed. Drainage catheters are placed around the heart … these are usually removed after 24 hours. Temporary pacing wires to regulate the patient’s heart rate are sewn to the surface of the heart … these are removed before the patient goes home.
Following the operation, patients are transported to the Cardiac Post-Anesthesia Care Unit, a specialized unit caring exclusively for open-heart surgery patients. Patients generally awaken from anesthesia 4-6hr after the operation. The following morning all drainage catheters and monitoring lines are usually removed, and patients are transferred to a standard hospital room in the cardiac recovery wing of the hospital. Patients undergoing a CABG operation are usually hospitalized for 4-5 days following the surgery. To see what to expect during the recovery of this operation, please refer to our education section.
Off-Pump Coronary Artery Bypass Grafting
Coronary artery bypass grafting (CABG) has conventionally been an operation that requires the use of the heart lung machine. For selected patients, surgeons have designed an innovative way to bypass blocked arteries on the heart without the use of the heart-lung machine … this operation is called “off-pump coronary artery bypass grafting” or “OPCAB”. Although indications for performing this procedure are more limited, and long-term results compared with conventional CABG are unknown, there are some patients who may benefit from this procedure.
The principals of OPCAB are in some ways similar to that of CABG … namely, that an artery from behind the breast bone and/or veins from the legs are used to “bypass” blood around coronary artery blockages. OPCAB is different from CABG in that the heart-lung machine is not used … this means that the special catheters and “cannulae” that are placed in and around the heart for a conventional CABG operation are not used … the heart continues to pump blood to the rest of the body, and surgeons must operate on a “beating heart”.
An advantage of OPCAB over conventional CABG is that it may eliminate some of the risks associated with using the heart-lung machine. In most patients these risks are very, very small … but in some older patients with significant atherosclerotic disease of their aorta, poor kidney function, or significant lung disease … these risks may be more considerable, and OPCAB might be a reasonable and safer approach than conventional CABG. There are many more variables that determine whether or not a patient would be an acceptable candidate for OPCAB … these issues are best discussed with your surgeon.
A disadvantage of OPCAB is that because the heart is not stopped, surgeons must perform delicate suturing on a “beating heart”. Consequently, stabilizing devices have been developed to help limit the motion of the heart as surgeons operate (see Figure 3).
The operation itself is similar to the CABG operation described above. General anesthesia is induced, and the patient is asleep for the entire course of the operation. The surgeon opens the chest by dividing the breast bone or sternum. An artery behind the sternum, the left internal mammary artery (LIMA), is taken down and one end prepared for bypass grafting. If more than one coronary artery will be bypassed, saphenous vein from the leg is removed and prepared for the additional bypasses.
A stabilizing device is now placed on the surface of the heart (see Figure 4), limiting the motion of the beating heart. The coronary arteries are opened beyond the sites of the blockage, and the open ends of the LIMA and vein grafts are sewn to the openings in the coronary arteries. These are called the “distal” anastamoses. Because the “inflow” through the LIMA is left intact, as soon as the LIMA anastamosis is completed, blood flow is established to that region of the heart. A vein graft however, is harvested as a “free graft” and has no “inflow” … therefore, after the “distal” vein graft anastamosis is constructed, the other end of the vein graft is sewn to the aorta (the main artery leaving the heart) in order to establish “inflow”. These are called the “proximal” anastamoses. At this point in the operation, blood flow has now been established beyond all the blocked arteries, and the heart has effectively been “bypassed”.
Drainage catheters are placed around the heart … these are usually removed after 24hr. Temporary pacing wires to regulate the patient’s heart rate, are sewn to the surface of the heart … these are removed before the patient goes home. The sternum and incisions are closed, and the patient is transported to the Cardiac Post-Anesthesia Care Unit, a specialized unit caring exclusively for open-heart surgery patients. Patients generally awaken from anesthesia 4-6hr after the operation. The following morning all drainage catheters and monitoring lines are usually removed, and patients are transferred to a standard hospital room in the cardiac recovery wing of the hospital. Patients undergoing an OPCAB are usually hospitalized for 3-4 days following surgery. To see what to expect during the recovery of this operation, please refer to our education section.
Endoscopic Vein Harvesting
Standard incisions for harvesting saphenous vein for bypass operations historically have been long incisions that run the length of a patient’s leg. Alternatively several smaller “skip” incisions can be made to provide a more cosmetic and less painful result.
MASA surgeons and Physician’s Assistants now utilize a new technology called Endoscopic Vein Harvesting that permits them to harvest a complete leg’s length of vein through a 1 or 2 small (1 cm) incisions. The incision can be made anywhere along the leg, and vein is removed using specially designed telescoping surgical and video equipment (see Figures 8 and 9).
In addition to reducing the size of the surgical scar, Endoscopic Vein Harvesting significantly reduces leg discomfort in the post-operative period, and is associated with fewer complications such as infection and hematoma formation. Although some patients are not candidates for Endoscopic Vein Harvesting, MASA Surgeons strive to provide this state-of-the-art technique for all bypass patients.