Medtronic Inc. on Thursday announced that its CoreValve transcatheter aortic valve will once again be sold in Germany, after a German court voided a lower-court ruling prohibiting the device's marketing and sales. The lower court had ruled that Medtronic infringed on a patent by Edwards Lifesciences. Edwards also makes a transcatheter aortic valve.

Medtronic had been prohibited from selling CoreValve in Germany since Aug. 26.

But, on Oct. 29, the European Patent Office issued a preliminary opinion saying that Edwards' patent is not valid. That opinion prompted a higher German court on Thursday to say it would not enforce the earlier patent infringement ruling.

The immediate impact for Medtronic is a return to the German market in what is becoming a more crowded field in the area of transcatheter aortic valve replacement (TAVR).

"Medtronic is very pleased with this decision as it will ensure that patients in Germany who need aortic valve replacement will have access to this lifesaving therapy," said Dr. John Liddicoat, senior vice president of Medtronic and president of the Medtronic structural heart business. "As a result of the ruling, Medtronic will resume distribution of the CoreValve System in Germany."

Medtronic said it will post a required bond as soon as possible and resume sales in Germany.

CoreValve is not yet commercially available in the United States. Edwards' Sapien transcatheter aortic valve is currently the only such valve approved for use in the U.S., and only for patients considered at extreme risk for requiring open heart surgery.

But Medtronic officials have said they expect CoreValve to win U.S. regulatory approval in 2014, joining a growing field of competitors for patients. Last month, Boston Scientific announced European approval of its Lotus transcatheter valve. Last year, St. Jude hit the European market with its Portico valve.

Aortic valve stenosis is a deadly narrowing of the aortic valve that obstructs blood flow from the heart. Half of those patients with aortic valve stenosis die within two years of diagnosis. An estimated 150,000 patients are diagnosed with aortic stenosis each year. About one-third to one-half of those patients do not get surgery.

Some patients are considered too sick to endure the trauma of having their chests cracked open. Transcatheter aortic valve replacement allows doctors to insert a new valve into the heart by snaking a catheter up into the patient through an artery in the leg or through an incision in the upper body. Patients can be home from the hospital within a couple of days, instead of weeks after the procedure.

Edwards and Medtronic have been the largest transcatheter aortic valve players in Europe, largely splitting what is estimated to be a $1 billion market. Analysts say the key to fully tapping what could become a $2.4 billion worldwide market will be expanding the number of patients who qualify for the procedure.

In addition to using the device on those patients deemed too ill to survive open heart surgery, medical technology companies continue to study using the device with patients who are considered lower risk — patients who have a better chance of surviving open heart surgery but for whom the TAVR technology is considered a preferable option.

In an interview last year, Dr. Keith Dawkins, global chief medical officer for Boston Scientific, said that as many as 30 percent of patients with aortic stenosis in Europe are being treated with transcatheter valves. The market is growing about 22 percent per year, he said.

Still to be determined is whether TAVR valves work as well as valves replaced the old-fashioned way. Doctors do not yet know how long these valves last. And local doctors say other issues to be addressed include the problem of replacement valves leaking and an increase in the rate of strokes for patients who have had TAVR.

On Thursday, analyst Dan­ielle Antalffy of Leerink Swann Research told investors that the ruling by the German court should prove "modestly positive" for Medtronic. Conversely, it could have a modest negative financial impact for Edwards, she said.