Hearts on Their Minds


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The Berlin Heart has been a literal lifesaver for young children with heart problems, as it's the only cardiac pump presently approved by the U.S. Federal Drug Administration. In fact, in the U.S., it recently kept a patient alive for more than 200 days. The problem is, this same invention that can keep a person alive also exposes patients to a 40% risk of thrombosis formation, creating a risk of stroke and embolism.

The goal of professors Alison Marsden and Yuri Basilevs is to limit the thrombosis risk of the Berlin Heart.
Images: UCSD

 

Alison Marsden, assistant professor of mechanical and aerospace engineering at University of California, San Diego, and Yuri Basilevs, associate professor in the Department of Structural Engineering at UCSD, combined their strengths in the hopes of reducing the thrombosis possibility. Marsden had a background in working with clinicians at both Stanford University and a children's hospital, modeling blood flow in the cardiovascular system and relating it to, among other things, surgery applications. Basilevs's strength is in designing computational methods for complex application.

The device has both a blood and air chamber with a membrane in between that provides a difficult challenge in discerning some pattern to why the thrombosis occurs. For Basilevs, he found that when it comes to membranes, you have to be careful when solving equations dealing in fluid. Adds Marsden: "It's difficult because the membranes have non-linear behavior."

The Berlin Heart pump. Image: UCSD

The research between their teams has created a working version of code that simulates the Berlin Heart. It's a start, but there's so much more if they hope to get to the finish. "The challenge is how to link it with the biological and clinical aspects in terms of taking output of simulations and assess risks and improve patient outcome," Marsden says, adding that a key is checking with clinicians to ensure what they're working on is realistic and all parameters are representative of real scenarios where they would use the device. Assessing the potential for clot formation will come down to linking fluid mechanics with the chemistry of formations, Marsden says.

Another benefit of their goal is training the students on their teams to understand the methods they're using to further the research. Talking about one of the leading researchers, Ph.D. student Chris Long, Basilevs says, "It's a chance to give him helpful skills in computational structural mechanics and fluid mechanics that he can apply to other problems."

The medical response to the work so far has been strong and has helped keep them motivated. "The clinicians I've worked with on simulations have been very receptive but we need to get it to the point where it will help them clinically," Marsden says. "We did simulate flow into specific arteries or veins and there has been direct work with clinicians. With medical devices, we have a mix of engineers who design but it would be good to establish with people who work in between the clinicians and us," says Basilevs.

Eric Butterman is an independent writer.

Assessing the potential for clot formation will come down to linking fluid mechanics with the chemistry of formations.

Alison Marsden, assistant professor of mechanical and aerospace engineering, UCSD

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January 2013

by Eric Butterman, ASME.org