66 THE SCIENTIST | the-scientist.com
READING FRAMEST
he heart is the first organ to form—
starting to throb approximately
three weeks into fetal development,
even before there is blood to pump—and
life ends when its beat ceases for good.
From birth until death in humans, the
heart beats approximately three billion
times. The amount of work it performs is
mind-boggling. Each heartbeat generates
enough force to circulate blood through
approximately 100,000 miles of vessels.
The amount of blood that passes through
an average adult heart in a week could fill
a backyard swimming pool.
So when the heart fails, the body fails.
Every year more than half a million Amer-
icans develop congestive heart failure,
in which the heart weakens or stiffens to
the point where it cannot properly pump
blood to meet the metabolic demands of
the body. The symptoms of end-stage heart
failure—shortness of breath, fatigue, nau-
sea—are some of the most torturous and
feared in the human experience.
Replacing the failing heart with an
off-the-shelf mechanical device has been
the great ambition of cardiologists and
cardiac surgeons for the past half century.
At first glance, the technological obsta-
cles seem insurmountable. Blood quickly
coagulates when it encounters plastic
or metal. Without adequate blood thin-
ning, clots can be expelled from an arti-
ficial heart and course through the body,
blocking arteries and causing strokes or
other damage. An artificial heart also can
never stop pumping, even temporarily,
so power lines must travel into the body,
posing the risk of infection.
But tremendous progress has been
made on this front. The first artificial
heart replacement in an animal was per-
formed at the Cleveland Clinic in 1957.
The organ, built by Dutch physician Wil-lem Kolff, held two balloon-like sacs filled
with blood inside its plastic ventricles.
Pressurized air filled the ventricles and
compressed the balloons, thus forcing
blood out in much the same way as from a
beating heart. Kolff ’s subject, a dog, sur-
vived for about ninety minutes.
Twelve years later, on April 4, 1969,
Denton Cooley, a surgeon at St. Luke’s
Episcopal Hospital in Houston, implanted
the first artificial heart, made of polyester
and plastic and powered by compressed
air, into Haskell Karp, a forty-seven-year-
old Illinois man suffering from end-stage
heart failure. After the implant, which
was intended to provide only a few days
of support, a frantic search for a donor
heart commenced. A compatible organ
was identified three days later in Boston.
It was transplanted successfully, but Karp
died thirty-two hours after the operation.
In the ensuing years many refine-
ments have been made to artificial-heart
design, including changing the shape of
the organ and developing more blood-
compatible building materials. Still, cul-
tural prohibitions have remained, slow-
ing progress. Many people continue to
be repulsed by the idea that the human
heart could be replaced by a machine
made of metal and plastic. For them, the
heart still carries special spiritual and
emotional meanings that make it impos-
sible to replace with a man-made device.
Research on artificial hearts contin-
ues today. The long-term support record
is held by an Italian patient who sur-
vived for 1,373 days before a successful
heart transplant. But significant obsta-
cles to a durable artificial heart persist,
including infection, bleeding, clotting,
and strokes. Today’s devices produce
continuous blood flow, so patients
emerge from the operating room with-out a pulse. The devices still pump
blood, of course, but the flow is con-
stant, not periodic. Incredibly, it’s now
clear that humans can survive for long
periods without pulsatile blood flow.
The workhorse of mechanical support
for heart-failure patients today is actu-
ally not the artificial heart but the left
ventricular assist device (LVAD), which
attaches to the native heart, pumping
blood directly out of the left ventricle and
into the aorta, thus essentially bypassing
the failing organ. LVADs have become a
lifesaving option for end-stage heart-failure
patients. Unfortunately, they are not a
viable option for patients with severe
failure of both right and left sides of the
heart. For such patients, a permanent
artificial heart may still be the best hope.
It remains a dream, but not quite the
pipe dream it was fifty years ago. gSandeep Jauhar is director of the Heart
Failure Program at Long Island Jewish
Medical Center. He is the author of Doc-
tored and Intern and writes regularly
for The New York Times. Read an excerpt
of Heart at http://www.the-scientist.com.Farrar, Straus and Giroux, September 2018In this adapted excerpt from Sandeep Jauhar’s new book, Heart:
A History, the author explores the past and future of artificial hearts.BY SANDEEP JAUHARRepeating the Beat