When people age, the main valve carrying blood out of the heart becomes brittle. As this aortic valve narrows, it can cause debilitating heart failure, and even death.

Fixing the problem in the United States requires open-heart surgery. In Europe, the problem can be repaired using a tiny catheter that introduces a replacement valve through an artery in the leg. In July, a Food and Drug Administration advisory panel said this device should also be approved for sale in the U.S. It is expected to reach patients by year end—more...