Peel off a few of the outer leaves or any that look discolored. Trim the bottom stem, leaving about a half of an inch. Trim the top of the artichoke as well, about a half an inch.
Gently loosen the artichoke up by pulling it apart with your hands (not completely, just enough so that it isn't as tight). This will help allow steam to get into the inner parts of the artichoke and for it to cook evenly.
Arrange artichokes cut side down. Add halved lemons along with garlic cloves that have been peeled and smashed. Pour water over top.
Attach pressure cooker lid and set for a cooking time of 15 minutes at High Pressure. When finished, quick release.