WHRT World Heart Corp. (MM)

World Heart Corp. (WHRT) has paused enrollment in a study of its Levacor heart pump, pending regulatory approval of refinements to the device.

The pump uses magnetic levitation to suspend the spinning impeller, its only moving part, where others use blood or mechanical bearings. The company says that's expected to provide improved blood compatibility. World Heart has been unprofitable as it is focused on development of the device.

The company said Wednesday design modifications will be "technically ready in the next two to three months," but the timeline for their implementation depends on approval by the U.S. Food and Drug Administration, the timing of which is uncertain.

Shares closed Tuesday at $1.86 and were halted premarket on the news.

 
   -By Matt Jarzemsky, Dow Jones Newswires; 212-416-2240; matthew.jarzemsky@dowjones.com