Split screen: An ultrasound device sends a constant stream of three-dimensional data from the patient’s heart to a computer, which splits it into a pair of slightly tilted images–one for each eye. Specialized glasses flicker back and forth between the left and right eyes while the two images flicker back and forth on a computer screen. The result is akin to a holographic video of the heart’s inner workings.
“Your brain knows how to integrate that information and give you depth perception automatically,” says del Nido. “You don’t have to have a computer that tells you you’re two and a half centimeters from the target–your brain intuitively figures that out, and it does it on the fly.” The result is a realistic, hologram-like 3-D experience.
Using this technology, the Children’s Hospital team built a custom-made display that could process data from an ultrasound probe. Then cardiac surgeon Nikolay Vasilyev donned a pair of stereoscopic glasses and tried out the display while operating on the beating hearts of pigs.
First, Vasilyev created a tear in the wall dividing the left and right atria, simulating a condition called an atrial septal defect. Then he repaired the hole with a tiny patch, fastening it in place with several tiny anchors. Because the entire surgery was performed with specialized tools that could be inserted through a very small opening in the heart’s surface, it was noninvasive enough to let the heart keep beating the whole time. In total, Vasilyev operated on six pigs: three with the stereoscopic display, and three with the regular 3-D display.
In all six surgeries, Vasilyev successfully affixed the patch, with no difference between the two groups in terms of how accurately he placed the anchors–perhaps because he has extensive experience with this particular procedure. But the new device did allow him to more precisely navigate his instruments to their destination–reducing the risk of damage to surrounding structures–and to get the job done 44 percent faster. The results of the study were announced yesterday in the Journal of Thoracic and Cardiovascular Surgery.
The stereoscopic system may help extend the uses of beating-heart surgery, expanding its use in children with congenital heart defects and in complicated heart repairs like extensive holes and faulty valves. Indeed, del Nido sees real-time stereoscopic imaging–combined with cutting-edge surgical instruments–as a platform that might ultimately revolutionize heart surgery the way that laproscopic procedures revolutionized abdominal surgery. “What we’re developing here is really a new platform for doing heart repairs in a very different way,” says del Nido. “We’ve taken the initial step: we’ve done the proof of concept. Now we want to start seeing how far we can go with it.”
“Is it going to be ready for prime time tomorrow? No, it’s not,” says Gillinov. “But could it open up a whole bunch of new ways to fix things in the heart? Yes.”