What if the heart is poked during the procedure pericardiocentesis?

See below: During pericardiocentesis the exploring needle is connected to an electrode which helps monitor the position of the needle. If the heart muscle is touched it can be immediately repositioned.

Depends: A simple poke of the muscle will likely be of no consequence. Nicking a coronary artery would be very rare but could lead to bleeding of an ischemic event. Making a hole in the atrium would likely require a formal surgical drainage procedure.