The federal Food and Drug Administration has authorized the first human test of a portable, battery-operated device designed to help a weakened heart pump blood, its manufacturer announced Thursday.

Thermo Cardiosystems Inc. of Woburn, Mass., said in a statement that the first implant of its ventricular-assist device would take place at the Texas Heart Institute at St. Luke's Hospital in Houston, where the device was developed.The device, powered by a portable battery pack, would allow cardiac patients awaiting transplants greater freedom of movement. Heart-assist devices in current use require a patient to be tethered to a cumbersome, external power supply.