At Boston Children’s Hospital Aerospace 3D Modeling Tools Help Surgeons Repair Hearts

August 4, 2020 by Vanesa Listek 3D Printing 3D Software Aerospace 3D Printing Featured Stories Medical 3D Printing

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Pediatric heart surgeon David Hoganson has been repairing congenital heart disease through innovation ever since he joined the staff at Boston Children’s Hospital in 2014. As a cardiac surgeon with a background in engineering and industry experience developing cardiovascular medical devices, Hoganson strives to develop novel approaches to improve the safety and effectiveness of cardiac surgery for some of the youngest patients at the hospital. Pediatric developments like patches for heart surgery that use newborns’ umbilical cord or cardiac devices that allow surgeons to predict the success of heart valve repairs did not only earn him awards but are also part of his motivation to provide compassionate care to neonates and children. Recently, Hoganson relied on tools borrowed from the aerospace industry to repair an 18-year-old patient’s enlarged right atrium that made the flow through his Fontan circulation very inefficient.

Fontan patients have previously undergone a Fontan procedure used to redirect the blood flow from the lower body to the lungs through a method that disconnects the inferior vena cava from the heart and routes it directly to the pulmonary artery through an extracardiac conduit, allowing blood from the lower body to flow to the pulmonary artery, and then to the lungs, without having to pass through the heart. This method usually leaves a single ventricle responsible for pumping blood to the body and studies have shown that patients with atriopulmonary connections can develop marked right atrial distension over time.

To come up with an ideal solution to help the young high-risk single-ventricle or Fontan patient from North Carolina, Hoganson turned to aerospace engineers at 3D software developer Dassault Systèmes, to use a very complex software for airplane wing engineering.

“We have been collaborating with Dassault Systèmes for over a year now, using some of their simulation and engineering tools to better plan complex operations,” said Hoganson, who is also part of the team at Boston Children’s Hospital Heart Center, the largest pediatric heart program in the United States. “When this patient came up, we were already well down the path of developing a process to make aortic arch patches prospectively designed to fit kids perfectly. So, when we determined he needed a cuff, which has complex curvature similar to the aorta patches, we realized we had the tools and expertise to create it.”

David Hoganson. (Image courtesy of Boston Children’s Hospital)

As reported by Boston Children’s Hospital, before creating the cuff, Hoganson and his team ran a series of computer simulations of the surgery procedure using Dassault’s software and also modeled the flow through the planned surgical reconstruction, which is now part of their standard procedure when planning for complex heart surgery. However, computer flow modeling through the patient’s Fontan circulation predicted a 15 percent energy loss by placing a transition cuff between the conduit and pulmonary artery branches.

Computer flow modeling predicted a 15% reduction in energy loss by placing a transition cuff between the conduit and pulmonary artery branches (Image courtesy of David Hoganson)

Hoganson explained that given the large size of the entrance into the pulmonary arteries (38mm diameter) compared to the size of the conduit (20mm diameter), a special cuff had to be designed to create a smooth transition between the conduit and the native pulmonary arteries. Focusing on 3D modeling and flow simulation, allowed the team to design a cuff to get the desired flow. But translating the particular shape of the cuff from a flat patch material into the actual cuff they needed was problematic. So, Hoganson turned to his partners at Dassault for help, and one of the aerospace engineers at the French-based company helped Hoganson and his team use a very complex software developed for airplane wing engineering to “unfold” the cuff on the computer and generate the shape necessary to recreate the cuff from a patch material.

“The whole process took a few weeks, as we made some improvements in the design,” explained Hoganson. “It was only possible because Dassault had developed this tool that involved highly complex math that designed how to patch wings using the stretchiness of the mechanical properties of the wing patch materials, which we could then use to incorporate the stretchiness of the aortic patch materials. We were grateful that they were willing to share this software and their expertise with us. When it came time for surgery, the outcome was phenomenal.”

Cuff design flattened to cut from patch material (left), and cuff model in 3D (right). (Image courtesy of David Hoganson)

While Hoganson was performing the surgery, a couple of the team’s engineers were observing the procedure virtually, as they routinely do, checking computer models and making sure everything was carried out as planned. The surgeon said that the cuff fit exactly as it was supposed to and that when they removed the clamps, everything worked perfectly.

The successfully implanted cuff was one piece of a much larger effort for Hoganson: “It’s just a snapshot of what we’ve been doing and what we’re working towards. We’re very excited about our continued collaboration with Dassault and applying these complex tools to make a measurable difference in our patients’ lives. Where appropriate, we’re trying to shift these efforts, and use these engineering tools to predict the best way to do surgery, and afterward to see if they accurately predicted the outcome. Ultimately we want to understand how we can rely on these tools to help make better decisions for our patients.”

Computer modeling shows the position of the designed cuff (Image courtesy of David Hoganson)

Hoganson also said they are working to apply the same workflow they used for this surgery to other surgeries they do more routinely. His team was recently funded to apply the technology to aortic patients in a clinical trial and plans to start with lower-risk arch patients and progressively move to more complex arch patients.

Coming up with creative solutions for patients who have uncommon problems is part of Hoganson’s mission. Along with Peter Hammer, a research scientist in the Department of Cardiac Surgery at Boston Children’s Hospital, he has brought together a team of engineers to utilize 3D modeling and simulation to enhance the Heart Center’s capabilities in pre-operative planning. They now have a consultation service for the Heart Center to create 3D models for pre-operative and intra-operative visualization of complex patient anatomy, and rely on computational fluid dynamics to model expected blood flow in patients who have only a single working ventricle. In a recent LinkedIn post, the specialist described how “these powerful computational methods allow us to plan surgical modifications that optimize flow balance to the pulmonary arteries and minimize power loss, leading to better patient outcomes.” 3D planning tools will help surgeons plan procedures and tailor treatments to the individual characteristics of the patients, driving the dream of more personalized medicine forward.