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Ultrasound Enhancing Agents for Pediatric Heart Patients

1/15/2021

Woman looking at computer screens

Could tiny fat bubbles improve echocardiograms in kids and teens?


From diagnosis before birth, children with congenital heart defects need frequent echocardiograms to evaluate their heart function, at least once a year and often far more  but images get harder to gather over time. Last year, Children’s Hospital Colorado became the first center in the U.S. to use a contrast-enhancing agent in pediatric heart patients. Now, they’re exploring new possibilities.

The difficulty of echocardiography as kids age

“Sound attenuates with distance,” says cardiac sonographer Tracy Hill. “It’s easy to get an image on an infant, because there’s not a lot of distance between the probe and the heart. As kids age, imaging gets more difficult.”

In some ways, echo assessments serve as the foundation of diagnosis and treatment. But they require data good enough to feed a complicated calculation involving multiple views.

“When they’re 15 or 16 years of age and they’ve had three surgeries, it’s hard to get good images,” says pediatric cardiologist Pei-Ni Jone, MD, former Director of Quality in Echocardiography. “If we can’t see it with ultrasound, then we need to send them to cardiac MRI, which takes longer and is much more costly. Sometimes they need to be intubated or require anesthesia.”

How ultrasound enhancing agents work

That was frustrating for Hill, who spent 10 years as an adult sonographer before transitioning to pediatrics. At UCHealth, adjacent to Children’s Colorado on the Anschutz Medical Campus, she’d used ultrasound enhancing agents.

Initially approved for use in the hepatic veins, ultrasound enhancing agents produce higher-contrast ultrasound images by filling the vein with microscopic bubbles of sulfur hexafluoride encased in a lipid compound. Rather than traveling through blood and echoing off tissue, soundwaves bounce off the bubbles — “They ring,” says Hill — producing an inverse image.

“It lights up the ventricles,” says Dr. Jone. “You can see the border of the muscle with nice, clean definition.”

Rolling out Lumason for pediatric patients

In December of 2019, Hill attended a talk with the manufacturer of one ultrasound enhancing agent, Lumason, and found out it was in clinical trials for pediatrics. By the time it was approved a month later, she and Dr. Jone had started a rollout plan to bring it to patients — making Children’s Colorado the first pediatric center using ultrasound enhancing agents routinely.

Hill was the first one trained, since she had some experience, but a dedicated team of sonographers soon followed, as did the clinic’s seven nurses, who administer the contrast via IV.

“Even when the image is decent, it can still be difficult to provide accurate measurements,” she says. “Ultrasound enhancing agents can improve accuracy and reproducibility of results.”

And the added accuracy helps specialists improve their clinical decision-making. The ultrasound-enhancing agents are approved for the left heart, but the team has also started working on applying them to other conditions where poor acoustic windows prevent accurate images of the heart: pulmonary hypertension, single ventricle disease and muscular dystrophy, to name a few.

“More and more of our heart patients are surviving into adulthood, and many of them have poor acoustic windows,” says Dr. Jone. “They need this. It’s time to use it.”