spanning four decades, evidence is emerging that
calls into question the ultimate effectiveness of
CABG in preventing deaths due to CAD. A num-
ber of studies indicate that CABG may not extend
LIFE EXPECTANCYor improve QUALITY OF LIFEto the
degree cardiologists and others believe it does.
Researchers continue to explore all dimensions of
this debate.
Surgical ProcedureThe typical CABG takes 75 to 90 minutes for the
surgeon to perform. The first steps in CABG are to
open the chest, initiate cardiopulmonary bypass,
and stop the heart. The preferred approach for the
grafts is to use the person’s own blood vessels to
reconstruct the occluded coronary arteries. The
most viable vessels for this purpose are the right
and left internal mammary arteries, which the
surgeon exposes when opening the chest to per-
form the CABG. These arteries are ideal because
they do not require additional incisions to obtain,
and there is a good supply of arterial circulation to
replace them. As well, the mammary arteries are
about the same size as the coronary arteries,
allowing them to accommodate the demands the
coronary circulation will place on them. The sur-
geon may be able to craft two and sometimes
three grafts using both internal mammary arteries.
Because of its size and importance to coronary cir-
culation, the LAD is first in line for an arterial
graft. The surgeon needs about 6 inches of graft
for each coronary ARTERYbypass created.
When the CABG involves more coronary arter-
ies than the mammary arteries can accommodate,
the surgeon typically harvests a segment of the
saphenous VEINfrom the leg, which requires an
incision in the groin. Though effective enough,
the saphenous vein graft is less than ideal for serv-
ice as a coronary artery and is more prone to post-
operative complications. Although its size makes it
a sturdy vessel, the saphenous vein lacks the mus-
cular construction of an artery and has a greater
risk of collapsing or closing than does an arterial
graft. As well, some people have residual edema
and other complications after surgery in the leg
from which the surgeon harvests the vein. An
alternative practice is to instead harvest segments
of arteries from elsewhere in the body for which
there is relatively redundant circulation (other
arteries to provide blood supply), such as the
radial artery or the brachial artery in the arm.
When autografts such as these are not possible,
the surgeon may use a synthetic material specially
treated to resist clotting. However, synthetic grafts
are not as reliable as autografts.
The surgeon sutures (sews) one end of the graft
into the AORTAabove the occlusion and the other
end into the coronary artery below the occlusion
to establish the bypassed path of circulation. The
surgeon does this for each occluded coronary
artery. When the internal mammary artery pro-
vides the graft, the surgeon needs only to suture
at the distal end because the proximal end is
already in place. The diseased coronary artery seg-
ments stay in place though will no longer carry
blood. When finished bypassing the occluded
coronary arteries, the surgeon restores blood cir-
culation through the heart and restarts the heart
with a chemical solution or an electrical charge.
After making sure the grafts are intact and not
leaking, the surgeon closes the chest. Wires hold
the ribs and sternum in place, while sutures and
staples close the layers of MUSCLEand SKIN.Risks and Complications
CABG entails numerous risks and complications.
Though its frequency gives the perception that it is
a routine operation, CABG is a significant major
surgery during which the surgeon places the per-
son on cardiopulmonary bypass, cuts through the
breastbone and several ribs to expose the heart,
stops the heart to reconstruct the coronary arter-
ies, and then restarts the heart and closes the
chest. Each step carries its own risks. Collectively,
the major risks of CABG include- air emboli (air bubbles that get into the blood-
stream and create blockages), causing heart
attack, STROKE, or PULMONARY EMBOLISM - excessive bleeding during surgery
- bleeding when the surgeon restores circulation
through the heart - inability to restart the heart
- inability to wean from the cardiopulmonary
bypass machine when surgery is done - postbypass neurologic damage with residual
consequences that may include cognitive dys-
42 The Cardiovascular System