3D modeling and virtual visualization takes cardiac surgery planning to the next level

3D modeling and virtual visualization takes cardiac surgery planning to the next level
Cardiac Surgery

Every millimeter counts in pediatric heart surgery, where a heart might be no larger than a walnut or a golf ball. That precision matters even more for novel procedures like mitral valve partial heart transplants or complex ventricular assist device placement.

Cardiac surgeons in the Children’s National Hospital Heart and Lung Center benefit from 3D modeling for complex surgical planning and patient education thanks to the work of specialized cardiologists and digital engineers in the center’s 3D Cardiac Visualization Laboratory.

The center has worked to incorporate clinical applications of 3D modeling for more than eight years. The work initially focused on the integration of physical 3D printed models for surgical planning. However, engineer Ryan O’Hara, PhD, says, many surgeons have transitioned to virtual versions of 3D models, displayed and studied in high definition on a screen or virtual headset, rather than a physical 3D print.

“Ninety percent of the work is the same for a virtual model,” he says. But the end result is more portable and removes the burden of waiting between 5 and 12 hours for a printer to bring a detailed model to life.

Why it matters

Those hours can be critical for surgeries on a timeline, such as partial heart transplants. Recently, Dr. O’Hara and Yue-Hin Loke, MD, director of the 3D Cardiac Visualization Laboratory, worked together to provide computed tomography (CT) based 3D visualization for the first mitral valve partial heart transplant at Children’s National. The case required exceptionally precise measurements as the surgery included the first replacement of an artificial mechanical valve with living mitral valve from a donor heart. The valve from the donor heart and precise areas of extra heart tissue were needed to rebuild structures of the heart that were no longer present after the patient’s existing artificial valve was placed. The surgeon wanted a geometrical twin of the patient’s heart to better understand how the donor valve would be transplanted.

The ability to produce highly detailed models in the virtual space allows surgeons to see realistic, 3D detailed structures inside the heart which typically don’t show well using more routine cardiac imaging modalities such as transthoracic or transesophageal echocardiogram. The models also allow surgeons to customize views of complex structures and offer tailored visual orientations of areas in and around the heart.

Dr. Loke says the technology is often used by the surgeons to assist with planning for many different procedures when the heart anatomy is complex. One cardiac surgeon, for example, used 3D visualization for planning ventricular assist device cannula placement to account for, and avoid, other heart structures during implantation.

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Children’s National leads the way

The application and speed of developing clinically relevant 3D models continues to grow. In early years, the team averaged 20 to 25 models each year. Today, they are on track to model closer to 50 models.

The key to their success, is the expertise of the embedded 3D lab and the dedicated engineer behind it, who reviews the computer-generated models and enhances specific areas of interest or focus. “He [Dr. O’Hara] is very engaged in the clinical space,” Dr. Loke says. “He talks to the surgeons directly, sees how things are done and can help think through what perspectives the visualization needs to include.”

That human aspect won’t be going away any time soon. Most existing machine learning models, like most other technology in the cardiac space, is based on the adult population. While some of the image rendering can be performed using machine learning, both Dr. Loke and Dr. O’Hara note that making the final product useful to pediatric cardiac surgical planning is “much more art than science.”