Dr. David Hoganson, a pediatric cardiac surgeon at Boston Children’s Hospital, is part of a team of surgeons working with the highest risk, most vulnerable patients, performing hundreds of procedures each year requiring meticulous planning and the highest level of expertise.
The heart is a complex organ, and the heart of a child is many times smaller, in fact in a newborn it is about the size of a walnut. For decades, surgeons have made decisions during surgery, while the patient is on the table. But, Hoganson and his biomedical engineering team led by he and Peter Hammer saw a better way, and began applying leading-edge virtual twin technology to model processes in advance of surgery and as a result, improving patient outcomes.
Over the past five years, Hoganson and his team have used technology typically associated with the aerospace and automotive industries to create specific, patient-centered roadmaps for surgeries long before the patient is brought to the operating room.
For Hoganson, who’s now director of the Computational 3D Visualization Program at BCH, the opportunity to virtually plan and test treatments is an opportunity to treat “not with hope, but with an exact plan.”
Putting virtual twins to work in healthcare
A participant in the Living Heart Project, an international effort spearheaded by Dassault Systèmes to develop a fully functional digital model of the complete human heart, Hoganson decided to do something that had never been done before. He and Hammer hired a team of engineers to bring advanced simulation technology to the medical world, creating three-dimensional models of individual patients’ hearts to improve outcomes in pediatric cases.
Hogan spoke about the team’s progress at the ninth annual Virtual Human Twin Experience Symposium earlier this year.
“We have a phenomenal group of professional engineers and this is their job, to make these models for these patients to utilize these very advanced CAD tools to perform virtual surgery, flow simulation and final element analysis,” Hoganson said. “It has been transformational for the heart center and I am excited some of these techniques are starting to be used by other centers also.”
Collaborating with Dassault Systemès has enabled Hoganson to focus on developing patient-centered and patient-specific modeling and simulation to “advance at a pace we would never have dreamed would occur”.
“The highest risk patients require meticulous planning that goes beyond experience,” he said. “Better planning equates better clinical outcomes. With this technology, we can make things we can control as perfect as possible.”
Virtual twins in healthcare: how it works
Using the 3DEXPERIENCE platform, engineers create virtual twins that show specific heart defects enabling Hoganson and his team to devise and practice patient-specific plans of action.
The process starts with a CT scan or MRI of the patient’s heart. A 3D model is created through a process called segmentation. Each area of the heart is shown in a different color. Surgeons can turn any component of the model on or off and get any cross-sectional, external or internal views of any anatomical feature.
In one example, a child with several holes of varying sizes between their mitral valve and pulmonary valve, he said, would need patches to enlarge the aorta and close the holes. The patches would need to be strong and flexible enough to stretch against the pressure of blood flow.
Hoganson explained: “The challenge is, when you operate inside the heart, or reconstruct the aorta or pulmonary artery, everything is zero pressure: flaccid. It is not the size and shape you are targeting.”
Dassault Systèmes’ modeling and simulation suites, CATIA and SIMULIA were used to ensure that the patch material, which starts out flat, would fold into the correct shape to meet the patient’s unique needs, he said.
“In 3DEXPERIENCE there is a phenomenal algorithm built for the aerospace industry that we’re using in cardiac surgery to flatten those patches and incorporate the mechanical properties of those patches,” Hoganson said. “Until now, we didn’t have any information the surgeon would need about how it flexes and how much it flexes.
“There’s been a lot of guesswork about trying to cut that patch. But now, the theory gets the curves correctly. The patch doesn’t buckle and it’s the right size. We were able to do that with a workflow that uses a number of very advanced aerospace tools within the 3DEXPERIENCE platform.”
Another example is the development of patient-specific mitral valve models for pre-operative planning and surgical guidance.
While the team has more than 900 models of ventricles, atria and blood vessels, it had been missing models of the valves, “a huge area of technical challenge for the field,” Hoganson said. Today, the engineering team creates patient-specific models of the mitral valve using their unique technique to create detailed, 3D maps, with all different aspects of valve disease.
“It has been transformational,’ he said. “It is changing the paradigm of how valve surgery is being done.”
Advancing care, changing lives with virtual twins in healthcare
There used to be up to a 40% incidence of injury to the heart’s electrical system during these complex reconstructive surgeries, resulting in a pacemaker for life, Hoganson said. The degree of accuracy possible today is leading to better outcomes for patients that will ultimately improve their lifetime outlook.
Over the past five years, the Boston Children’s Hospital cardiac team has created over 900 virtual twins for young patients with life threatening conditions, enabling a team based approach including other cardiologists and surgeons, as well as helping patients’ families understand and feel included.
“I can tell you it is absolutely phenomenal to go in with a well-designed plan as opposed to making it up as you go, which is what we’ve done for decades,” Hoganson said. “I owe it to my patients to perform the best surgery possible, and now that I know what is possible, I have no other choice.”