Color-coded vessels and airways printed in polyurethane show
the delicate relationships interventionists need to plan for when
implanting a device.
Soft models mimic the feel of cardiac structures and help surgeons get a
visual and tactile sense of a patient’s anatomy before they operate.
Dr. Morgan thought 3DRA imaging could be enough. Cutting out
traditional biplane imaging would mean less radiation, both for the
patient and for everyone in the lab. It would mean less procedural
time, a quicker recovery, less time in the hospital.
But 3DRA is tricky, a complicated setup further complicated by
the fact that the heart beats. By the time contrast is injected, the
team has about one second, maybe two, to get the image before
the contrast floats away. Some cath teams have dealt with that by
pacing the heart so fast it effectively doesn’t move blood.
Dr. Morgan wasn’t a fan of that approach. “It’s not very good for
you,” he says. “Plus if you stop the heart pumping you’re not getting
true anatomy. The heart’s pumping all the time. We want to know
what it’s doing when it’s doing that.”
“It took us probably two years of trial and error,” says Dr. Zablah.
“Optimizing the amount of contrast, where to give it, with which
catheter, based on size and lesion.”
It helped to work in a high-volume center — the team at Children’s
Colorado performs more than a thousand catheterizations
every year. They tested minute variations on hundreds of cases,
validating 3DRA against traditional angiograms until they knew
without a doubt they were just as accurate, even better. Dr. Zablah
literally wrote the protocols.
“We’re doing pulmonary valve placement with 75% less radiation
than any other center,” Dr. Zablah says. “Sometimes with no
contrast at all.”
Their 3DRA capability got so good, so precise and so fast, in fact, Dr.
Zablah started thinking about how to make it do more. Then she
woke up one morning with an idea.
Technologically, 3DRA and CT have a lot in common. Both rotate
X-ray around a central axis. But where CT is diagnostic and
logistically cumbersome, requiring radiology support and an
additional appointment of at least 45 minutes, 3DRA happens
in about 5 seconds as a routine part of every cath procedure at
Children’s Colorado. If Dr. Zablah could segment those images like
CT scans, she reasoned, she could build detailed 3D models, even
print them. They could use them to practice procedures and give
them to surgeons for planning operations.
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