Physicians from Children’s Hospital Boston, aided by a Harvard engineer who tinkered the output of an ultrasound machine to provide two slightly different angles of view at the same time, have been performing test surgeries wearing stereoscopic glasses. So far the initial evidence seems to show that the technology allows the surgeon to be more efficient with time and precise with technique.
From Children’s Hospital Boston:
The researchers, led by Pedro del Nido, MD, and Nikolay Vasilyev, MD, of Children’s department of cardiac surgery, had already been testing a three-dimensional ultrasound imaging system. But although the images are 3D and displayed in real time, they give little indication of depth. In animal tests, surgeons trying to navigate surgical tools inside the heart became disoriented when guided by these images.
Del Nido, chief of Cardiac Surgery at Children’s, realized that what they needed was stereoscopic vision. Watching the flat picture on the computer screen was like watching a baseball game on TV, he says. “It’s good enough to follow what’s happening in the game, but you could never grab a ball in mid-flight,” del Nido explains.
So collaborator Robert Howe, PhD, of Harvard University, plucked a solution from video games – splitting computer images in two and cocking them at slightly different angles. When wearing gamers’ flickering glasses, users can see ultrasound images of the beating heart as a hologram. “You definitely have depth perception,” says Vasilyev. “You feel like you’re inside the heart chamber.”
Vasilyev tested the glasses while operating on pigs with an atrial septal defect, a common form of congenital heart disease in which there is a hole in the wall dividing the heart’s upper chambers. Vasilyev closed each defect using a catheter carrying a tiny patch, threaded into the heart through a vein. Using another device, he fastened the patch around the hole with tiny anchors. In all, he placed 64 anchors: 32 under standard 3D ultrasound guidance, and 32 using the stereoscopic vision display.
Using the stereoscopic display, Vasilyev was able to place the anchors 44 percent faster than with the standard display (9.7 versus 17.2 seconds). The tip of the anchoring device also navigated more accurately – deviation from the ideal path averaged 3.8 millimeters, as compared with 6.1 millimeters, a 38 percent improvement.
The accuracy of anchor placement didn’t differ significantly between the two sets of tests, perhaps because of Vasilyev’s high level of experience and the availability of tactile information to help guide the final step of driving in the anchors. However, the speed of the anchor placement improved significantly. The researchers believe that the ability to precisely navigate tools inside the beating heart will minimize risk to neighboring heart structures.
Press release: Video game technology may help surgeons operate on beating hearts …
Image caption: Volumetric data on the atrial septal defect (arrowheads) are streamed in real time from an ultrasound system to a graphics station computer, which renders left-eye and right-eye views by alternating the position and orientation of the image, skewed by angle a. The rendered volumes, immediately displayed on a conventional monitor, are synchronized with flickering shutter glasses worn by the surgeon, yielding stereo-rendered 3D ultrasound images. This imaging technology provides surgeons with significantly better spatial information and depth perception for making repairs inside the beating heart. (LA, left atrium; RA, right atrium.) (Image courtesy Nikolay Vasilyev, MD, Children’s Hospital Boston)