An apparatus includes a catheter shaft assembly and an end effector. The catheter shaft assembly includes an outer sheath with a distal end. The end effector is associated with a distal end of the catheter shaft assembly. The end effector includes a plurality of leaflets. The leaflets are configured to transition between a first configuration and a second configuration. The leaflets are configured to fit within the outer sheath in the first configuration. The leaflets are configured to expand outwardly away from the longitudinal axis in the second configuration in response to being exposed distally relative to the distal end of the outer sheath. Each leaflet includes a flexible body and a plurality of electrodes. Each flexible body defines a plurality of openings. The electrodes are positioned on the flexible body.