The Orioles designated Heasley (shoulder) for assignment Wednesday.
The transaction frees up a spot on the 40-man roster for right-hander Chayce McDermott, who was called up from Triple-A Norfolk to start Wednesday's game in Miami. Heasley had been on Triple-A Norfolk's 7-day injured list for more than a month with right shoulder inflammation and was recently transferred to the 60-day IL, so he won't be eligible to pitch again until at least mid-August.