Traditional open-heart surgery with a heart-lung machine is
still the gold standard.
Innovation doesn’t always mean improvement.
That’s the lesson we’re learning about off-pump bypass surgery.
This so-called beating heart surgery was developed in the 1990s
as a novel way to reroute blood flow around cholesterol-clogged
coronary arteries. But it hasn’t replaced the original version,
in which the heart is stopped and a machine pumps blood around
the body. In fact, a major study suggests that off-pump bypass
surgery doesn’t quite measure up to the traditional operation.
A vast network of arteries delivers oxygen and nourishment to the
billions of cells that make up the heart. It starts at the aorta,
the main pipeline for oxygenated blood that emerges from the
powerful left ventricle. The right coronary artery and left
coronary artery branch off from the aorta and subdivide into
progressively smaller vessels. Some hug the surface of the heart;
others burrow into it.
The buildup of fatty deposits, called plaque, on the inner walls
of coronary arteries can hinder blood flow. A plaque-narrowed
artery may work just fine when the body is at rest. But when
exercise or stress makes the heart work harder, the clogged
artery may not be able to deliver as much oxygen and energy as
its part of the heart needs. This causes the chest pain or
pressure known as angina, or other symptoms such as shortness of
breath, sudden nausea, pain in the left arm or jaw, or anxiety.
Before the 1950s, rest and symptom-stopping medications like
nitroglycerine were the only remedies for angina. The invention
of the heart-lung machine made a surgical fix possible. Using a
small section of artery or vein taken from elsewhere in the body,
a surgeon could reroute blood flow around the clogged artery. The
heart-lung machine, by mechanically circulating blood around the
body, allowed surgeons to temporarily stop the heart from
beating. This made it much easier to sew together blood vessels
as small and slippery as cooked spaghetti with thread as fine as
a human hair.
Conventional bypass surgery
In on-pump bypass surgery, the heart is stopped and a
machine circulates blood around the body. This gives the
surgeon a steady, bloodless field on which to operate.
Of course, coronary artery bypass surgery isn’t a magical,
wave-of-the-wand cure. A small percentage of patients die during
the operation or soon afterward. Some have a stroke or develop an
infection. Others experience a mental fog that can last for a few
weeks or longer. Some experts blamed the heart-lung pump for the
apparent change in thinking skills. Others thought it might be
due to clamping the aorta and connecting it to the machine, which
can release small chunks of plaque into the circulation. If these
settle in the brain, they can hinder blood flow to parts of the
brain and slow down the nerve connections that drive thinking.
Surgeons, engineers, and inventors tinkered with all aspects of
standard bypass surgery, looking for ways to make it safer. One
result was beating heart surgery, which didn’t require the use of
the heart-lung machine. This off-pump bypass surgery begins in
much the same way as a standard bypass operation, with an
incision called a sternotomy that opens the breastbone and
exposes the fist-sized heart muscle beneath it. But instead of
stopping the heart, the surgeon applies a special tool that
isolates and stabilizes only the small section of the heart
around the diseased artery. As he or she bypasses the blockage
with a graft, the rest of the heart keeps on beating away,
circulating blood as usual. The stabilizer is moved as needed for
a second, third, or even more grafts.
Off-pump bypass surgery
In off-pump bypass surgery, a stabilizer immobilizes the
part of the heart with the diseased coronary artery. The
surgeon performs the bypass graft while the rest of the
heart continues to beat and pump blood around the body.
Coming into focus
Early reports about off-pump bypass surgery were pretty positive.
Short-term survival and stroke rates were much the same as they
were for on-pump bypass surgery, but it seemed as though the new
technique better protected the brain.
As word spread, more and more surgeons learned how to do the
off-pump bypass procedure. Some believed the procedure was
better, even though the early studies were a bit shaky, and there
were no long-term data. Others did it to expand their repertoire
or tackle a new challenge. Some hospitals jumped on the
bandwagon, billing the off-pump bypass as the “executive bypass”
for people who couldn’t afford to slow down after the operation.
Larger, longer studies muddied the water. Some showed less loss
of memory and thinking skills after off-pump bypass; others
didn’t. A few studies raised concern that surgeons did fewer
grafts when using the off-pump technique, which could leave some
blockages unfixed. A statement from the American Heart
Association in 2005 called the controversy over which procedure
was better “one of the most hotly debated and polarizing issues
in cardiac surgery,” and concluded the two procedures were
The results of a large trial conducted at 18 Veterans Affairs
(VA) medical centers across the country are bringing some clarity
to the debate. In this trial, 2,203 veterans in need of a bypass
were randomly assigned to on-pump or off-pump surgery. At 30 days
after the procedure, the results were almost identical — similar
numbers of deaths, strokes, cardiac arrests, cases of kidney
failure, and reoperation in both groups. One key difference,
though, was that 18% of the off-pump group ended up getting fewer
bypass grafts than originally planned, compared with 11% of the
on-pump group (New England Journal of Medicine, Nov. 5,
A year later, other important differences had emerged. In the
off-pump group, 9.9% of the participants had died, had a heart
attack, or needed another procedure to open or bypass a blocked
coronary artery, compared to 7.4% in the on-pump group. Follow-up
angiograms showed that the grafts were somewhat sturdier and
tighter in the on-pump group. And there were no differences
between the groups in scores on a battery of tests designed to
assess memory and thinking skills.
Trial raises questions
The VA trial wasn’t perfect. Critics argue that some of the
surgeons doing the off-pump procedure didn’t have enough
experience, and the results would have been better if only
surgeons who had done at least 50 or 100 operations (instead of
at least 20) had been included. The study population is another
problem. Although earlier studies had suggested that off-pump
bypass surgery may benefit women more than men, and individuals
with other illnesses in addition to coronary artery disease, the
VA trial included mostly men who were younger and healthier than
the average candidate for bypass surgery.
Even so, the findings give us pause about off-pump bypass
may prevent a surgeon from creating grafts for all the
blockages. This could leave part of the heart still starved
at times for oxygen-rich blood.
could hinder the creation of smooth, even connections between
a graft and a coronary artery. Even a small pucker in the
stitching can roil blood flow, which would accelerate the
formation of new plaques.
doesn’t protect against bypass-related thinking problems
(what doctors once referred to as “pump head”) better than
traditional bypass surgery using the heart-lung bypass
What do you really need?
Off-pump bypass surgery clearly isn’t better than
traditional bypass surgery. When performed by equally experienced
surgeons, on-pump and off-pump bypass surgery yield the same good
results. That means finding an experienced surgeon, and surgical
team, is an essential part of the preoperation process. “Bypass
surgery is a team effort,” cautions Dr. Kamal Khabbaz, chief of
cardiac surgery at Harvard-affiliated Beth Israel Deaconess
Medical Center. “You want to make sure that the surgeon works
with a stable team and they have done this operation together
many, many times.”
If you have angina or other signs of a clogged coronary artery,
it’s a good idea to ask yourself and your doctor a few questions,
says Dr. Deepak Bhatt, associate professor of medicine at Harvard
Medical School and chief of cardiology for the VA Boston
Healthcare System. He suggests these three for starters:
Do I really need bypass surgery? If you
aren’t having any symptoms of coronary artery disease, neither
bypass surgery nor artery-opening angioplasty will do you much
good. Medications and lifestyle changes, like more exercise and a
better diet, offer a more effective way to prevent a heart attack
What’s my coronary anatomy? An
angiogram showing blood flow through the coronary vessels can
determine that angioplasty is the way to go or reveal that bypass
is a better choice.
What’s my overall risk? If you are at
high risk for bypass-related problems, perhaps because you have
failing kidneys or have recently had a stroke, then angioplasty
might be a better option than off-pump bypass surgery. “I don’t
think the off-pump procedure should be thought of as a middle
ground for high-risk patients,” says Dr. Bhatt.
If the off-pump bypass procedure is the one your cardiac surgeon
is most comfortable with, and he or she does it often with an
experienced team, it’s a perfectly fine choice. But there is no
compelling reason to pursue this new procedure, either. For now,
the old standby — which itself was once a revolutionary new
technique — is still the gold standard.
As a service to our readers, Harvard Health Publishing provides access to our library of archived content.
Please note the date of last review or update on all articles. No content on this site, regardless of date,
should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.