An apparatus includes a catheter shaft assembly and an end effector positioned at a distal end of the catheter shaft assembly. The end effector includes a balloon, one or more electrodes on the balloon, and a tip assembly at a distal end of the balloon. The balloon defines an interior configured to receive a fluid to inflate the balloon. The balloon is sized and configured to fit within a cardiovascular anatomical structure. The tip assembly includes a pressure relief valve that is configured to transition between a sealing state and a pressure-relieving state. In the sealing state, the pressure relief valve is configured to prevent fluid from leaking out from the interior of the balloon via the pressure relief valve. In the pressure-relieving state, the pressure relief valve is configured to provide a path for fluid to leak from the interior of the balloon via the pressure relief valve.