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With the pig's heart pumping, the device cut a small hole in the wall between the two upper chambers before being removed.
The successful test, which mimicked a procedure to fix a heart defect in children, showed that the device could one day be used on a range of operations, including those that currently require cutting open a child's chest and ribs to get at the heart.
A team of researchers led by Pierre Dupont at Boston Children's Hospital built and tested the device, which consists of a long tube with cutting teeth at the end (see diagram). Surgeons can use external ultrasound images to guide it to the heart, and then switch the teeth on remotely (The International Journal of Robotics Research, doi.org/wmc).
To make such a small and dexterous cutting tool, Dupont's team turned to a technique called microelectromechanical systems. This allowed them to build the tool by laying down layers of metal and create moving parts that are only a few microns across.
The tubular section of the device is strong enough to hold the heart tissue in place while it's beating, allowing the cutting head to remove tissue. Pieces that are cut off are whisked down the tube and out of the body. This could be particularly useful for an operation called a septal myectomy, in which excess heart muscle needs to be cut away to restore blood flow to the body.
Sam Kesner, a bioengineer at Harvard University's Wyss Institute, says the device is unique because the tubing that slides it into the heart is stiff enough to give the cutting tool purchase. "Normal catheters can't provide a lot of force. Cutting tissue away is very hard," he says.
This article appeared in print under the headline "Heart ops shrink thanks to surgeon in your vein"