“Surgeons say the holograms are a dream come true,” said lead author Dr. Henrik Brun, pediatric cardiologist, The Intervention Centre, Oslo University Hospital, Oslo, Norway. “Heart problems in children are very individual and the hologram helps them to make a detailed plan based on the anatomy of that specific child’s heart.”

Pediatric cardiologists and surgeons have been using 3-D printed heart models for surgical planning for several years. The printed models are based on standard images taken in children scheduled for surgery, such as a computed tomography (CT) scan or magnetic resonance imaging (MRI) of the heart.

Holograms can be produced using the same images. The hologram is seen as part of the real surroundings by wearing glasses. Compared to 3-D printed models, holograms are quicker and cheaper to produce, more interactive, and may be easier to share.

For this proof-of-concept study, mixed reality holograms were constructed for three patients with different congenital heart defects using images from MRI or CT. Applications (apps) were developed to allow surgeons to manipulate the hologram; for example—rotate it, and cut it.

The researchers then tested whether it was feasible to use the hologram in different locations, including the meeting room where surgeons and cardiologists discuss each patient, the operating room, and the catheterization lab for minimally invasive procedures. They also examined the usefulness of the apps.

They found that the holograms could easily be viewed in different clinical areas of the hospital. They could also be viewed simultaneously by cardiologists and surgeons for detailed studies of the heart’s anatomy.

“Our surgeons immediately wanted to use the holograms for planning how best to treat patients,” said Dr. Brun. “They said they have been looking for something like this for 20 years. They can study the hologram and imagine in detail how they would do an operation.”

Further apps are being developed, such as artificial heart valves, that can be added to the hologram to check the size and orientation. Virtual surgery is being tried out on the hologram to test a procedure’s suitability for that anatomy.

“We can now simulate operations on the hologram using the apps,” continued Dr. Brun. “Several shapes and positions of prostheses can be tested to see if they are a good or bad fit. Some hearts are so complex that a repair seems impossible, but I think virtual surgery will help us to operate in some of these scenarios.”

Future studies will investigate the impact of using the hologram on surgical decision-making—in other words, whether it changes the surgeon’s way of encountering an anatomic problem. Ultimately, the researchers aim to study whether using the holograms for surgical planning leads to better outcomes.

Dr. Brun added that virtual holographic surgery could be used to train young surgeons in surgical decision-making, 3-D visualization of an operation, and new techniques. “When you’re a young surgeon, you want to be clever when you do your first operation,” he said. “You don’t want to train on patients because you want everything to be perfect every time, and holograms offer a safe environment to learn.”

Experienced surgeons may be able to try out different solutions for rare and complex procedures rather than making decisions intraoperatively, which should shorten the operation time. Dr. Brun said: “Complex congenital heart surgery is different every time, and extremely thorough planning is a prerequisite for a good result. This small study shows that mixed reality holograms are still in the process of evaluation but may have a strong potential to assist planning of complex heart surgery in children.”