Operating inside a Beating Heart

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After studying the motion of real hearts, the researchers developed a foam model to test whether their device increased the dexterity of a small group of surgeons asked to affix anchors to the foam in particular positions. Howe says that the surgeons' performance was notably improved when they used the motion-compensation system. "Without it, there was a far higher failure rate, and the forces they applied were much higher as well," he says. In a clinical setting, applying too much force to the valve could damage heart tissue. Howe says that the system allows surgeons to affix the anchors within one to two millimeters of their intended position, which is fine, given the pliancy of heart tissue.

"It is very promising research," says Cenk Cavusoglu, an associate professor of electrical engineering and computer science at Case Western Reserve University. Cavusoglu is working on a similar system to allow surgeons to perform coronary-artery bypass surgery. While the procedure itself is quite different, the need for motion compensation is the same. Cavusoglu says that he is impressed by the simple design of the valve-repair tool and by the researchers' results so far.

Shelten Yuen, a Harvard PhD student who worked on the motion-compensation system, says that preliminary animal trials have already begun. But there is still much work to be done to perfect the tool. "There's a lot of interest on my part in terms of incorporating additional sensors, such as electrocardiograms and force sensors," Yuen says.

Romuald Ginhoux, a medical-software systems analyst at Median Technologies, in France, agrees that additional sensors could make the system more accurate. Ginhoux was also impressed by the small size of the device, which is about as big as a soldering iron. Ginhoux says that back in 2003, he worked on similar robots for heart surgeries, but that they were "the size of a real arm."

Yuen says that he hopes to make the device even smaller and lighter so that it will respond better to slight pressures, giving surgeons a better feel for the heart's tissue.