PALO ALTO, Calif. — Stanford University offers doctors a “room” with a unique view — the inside of an infant’s beating heart, valves opening and closing, blood cells rushing past. (Well, it’s unique if you discount the campy 1966 sci-fi thriller, “Fantastic Voyage.”)

The virtual reality project tackles what has always been a major challenge for medical trainees: how to visualize a heart in action in three dimensions. Through VR goggles, they can now travel inside the heart and explore congenital heart defects as if they have been shrunken to the size of a peanut.

“I can literally see where the blood’s coming from and where it’s going in a way that I never had,” Dr. Christopher Knoll, a Stanford pediatric cardiology fellow, said after trying out the prototype system last week for the first time.

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When Dr. David Axelrod, who helped develop the virtual heart teaching tool, asked Knoll if he was ready to return to the real world, Knoll resisted. “No, I like it!” he said with a laugh.

The VR system is part of a growing push to use immersive 3-D visualization technology to improve medical and patient education. Microsoft’s HoloLens is being tested at Case Western Reserve University for teaching medical students anatomy and physiology, and a University of Michigan project takes doctors inside the brain to gain insights for treating migraine headaches.

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The CT scan, echocardiogram, and MRI will remain crucial tools for diagnosis and treatment, but some experts think VR visualization could soon become an essential supplement for heart doctors and surgeons, and a way to reduce reliance on cadaver dissection for teaching.

The Stanford project and similar efforts are “where the future is,” said Dr. Luca A. Vricella, chief of pediatric heart transplantation at Johns Hopkins University School of Medicine, noting that getting a 3-D image in one’s mind is crucial for medical trainees to understand heart surgery. “It gives you a much better understanding of what you will be looking at in the operating room.”

Doctors at Lucile Packard Children’s Hospital gave KC Grewal these drawings to help explain her son’s heart condition. The Stanford VR system enhances that instruction with an immersive, interactive experience. Jason Henry for STAT

Put the Stanford VR goggles on, and you find yourself in a well-lit doctor’s waiting room, standing on a central dais. On the left you see wall-mounted flat images of hearts, and on the right, a multi-color plastic heart model — homages to old-school visualizations of heart defects and blood flow.

Straight ahead, a shelf holds a dozen 3-D hearts, labeled by congenital defect. Hit the trigger of a hand-held controller, and you drag a “living,” beating heart from the shelf so it hovers in front of you. The heart can be spun on its axis or exploded into sections that continue their synchronized beating — showing both internal and external features. You can “grab” a section with another command and turn it over or around to see it from any angle as it continues to pulsate, almost like it’s a small living creature.

One model shows a ventricular septal defect — a hole between the two ventricles, or main heart chambers. This birth defect causes some oxygen-rich blood to be pumped back into the lungs rather than to the rest of the body — an inefficient step that can cause the heart to overwork.

With the push of another button, you “teleport” inside the heart and see blood cells streaming through the hole between the chambers. With another button you can “surgically” fix the defect, making the heart normal.

Users don’t get dizzy or develop motion sickness, because they are stationary inside the heart, with structures moving around them, in contrast to being on an amusement park ride.

So far, Stanford has prototypes that show the ventricular septal defect and one other type, with a goal of rolling out the 25 to 30 most common heart defects soon. The long-term goal, Axelrod said, is to add models for adult heart diseases, and eventually those of the lung and brain.

Even advanced imaging methods can leave gaps in how clinicians understand a surgically corrected heart’s structures, said Axelrod, a pediatric cardiologist at Stanford’s Lucile Packard Children’s Hospital. “If you can’t understand what the geometry is, what the anatomy and physiology are of the heart, you can make a mistake” in later treatment, he said.

Az Balabanian/UploadVR

The Stanford system was built with the San Francisco-based software company Lighthaus, which Axelrod owns shares in and advises. It was funded by Stanford’s Division of Pediatric Cardiology and Facebook’s Oculus VR subsidiary.

The technology can also help patients grasp how surgeons repaired the defects in their hearts. “I see patients every week that come in with a scar on their chest, and they’re 20 years old, and I’ll say, ‘What surgery did you have?’ — and they have no idea,” Axelrod said. “It’s our job to help them understand their heart problem, because we think you get much better care if you know what’s going on.”

Within five years, individualized VR programs informed by diagnostic scans could be ready, Axelrod said. “I will be able to say, this is your virtual heart.”

Dr. Jamil Aboulhosn, who directs a congenital heart disease center at the University of California, Los Angeles, cautioned that immersive 3-D technologies should be regarded as an adjunct, rather than a replacement, for more traditional ways of studying anatomy and physiology that have served medicine well for decades.

“I have been a little bit concerned as we move toward everything becoming 3-D and virtual reality, that we are moving into an era of simplification — ‘Let’s just make something look really cool,’” he said. But it’s not yet time for medical schools to dispense with teaching human anatomy through the painstaking dissection of cadavers.

“Yes, virtual reality is ready for prime time. Yes, it’s exciting,” Aboulhosn said. “Will it make everything that came before obsolete? No.”