Doctors at a New York university kept the heart of a dead man beating to test a new drug designed to prevent blood clots that can lead to heart attacks or strokes, a medical journal reported. An editorial accompanying the article in the Annals of Internal Medicine called the experiment “ethically questionable.” Researchers at the State University of New York at Stony Brook and Centocor, a pharmaceutical firm in Malvern, Pa., said the test successfully prevented the man’s blood from clotting during the hourlong experiment. The new drug, called 7E3, also did not cause excessive bleeding, one possible side effect of two commonly used anti-clotting drugs, heparin and warfarin. Experimenters used a portion of a monoclonal, or single-cell, antibody to block the clotting action. Monoclonal antibodies are called “magic bullets” because they seek out a specific kind of cell.