They believe they have found a way to replace heart valves without intrusive open-heart surgery.
A replacement heart valve is sewn into a stent, which is attached to a catheter. Then, through an artery in the leg, the catheter is carefully threaded up to the heart valve.
The stent expands and the new valve does its job.
"In my career, it's probably the biggest thing to come along since heart transplants, which is now quite a few years ago," said Craig Smith a doctor at New York's Columbia Presbyterian where experimental procedures are taking place.
Doctors predict that once it is approved more than 100,000 Americans a year could get this procedure done.
