BOSTON, JAN. 12 -- Two calves lived for seven weeks after a new, self-contained electric artificial heart pump was implanted in each of them, researchers announced today. Scientists said the test with the calves is a critical step before the experimental device can be tested on humans.

"It's a milestone of sorts," said Dr. William F. Bernhard, a heart surgeon at The Children's Hospital in Boston who implanted the devices. "Finally, we got the whole system together in an animal. And it ran well."

The pump, known as a left ventricular assist device, is designed for the estimated 15,000 Americans suffering from end-stage heart disease whose hearts are too weak to keep them alive but strong enough to function with help.

Air-powered assist devices are currently used for such patients to keep them alive until they can undergo a heart transplant.

The new device has an internal electric power supply that enables patients to avoid bulky air pumps attached by tubes through their skin. The absence of tubes or wires through the skin should reduce the chances of infection, Bernhard said.

The device consists of a pump, motor and computerized controller and is implanted into the abdominal area. It is attached to the ventricle of the heart and the aorta, the main artery from the heart.

A small battery in the device can allow the pump to operate without external power in an emergency for as long as 40 minutes, Bernhard said. Normally the device receives power from an external battery worn by patients on a belt or in a vest. The power is transmitted from the battery pack to the device through the skin using two coils. One coil is implanted under the skin, and other lies outside the skin. The external battery has up to 12 hours of power.

Bernhard said that if tests of the device, developed by Thermedics Inc., proceed on schedule, human implantation could start in 1989.