The patient:

William J. Schroeder, 52, of Jasper, Ind., who has battled heart disease for two years. He was forced to retire in 1983 from his job as a quality-assurance specialist at Crane Army Ammunition Activity. Married for 32 years, he is the father of six and the grandfather of five. The place:

Humana Hospital-Audubon in suburban Louisville, a 484-bed, for-profit institution under the auspices of he large hospital chain Humana Inc. The company has pledged to underwrite up to 100 mechanical-heart operations. The surgeon:

Dr. William C. DeVries, the only surgeon in the country authorized by the government to implant an artificial-heart. DeVries, 40, came to Louisville last summer from the University of Utah, where in 1982 he performed the first artificial-heart implant. The Jarvik heart:

A two-chambered, polyurethane-and-aluminum device developed by Dr. Robert K. Jarvik. It is an updated version of the Jarvik-7 that is driven by a refrigerator-sized air compressor. It can be hooked up temporarily to a portable unit the size of a camera bag. The history: The first artificial-heart recipient, Barney B. Clark, lived 112 days with the device. He died March 23, 1983. Animal reserach on the heart began with the implanting in 1957 of a device in the chest of a dog who survived with it for 90 minutes.