An ablation catheter including an elongate shaft, an inflatable balloon positioned at a distal region of the elongate shaft, a first ablation electrode disposed outside of and carried by an outer surface of the inflatable balloon, a first ultrasound transducer disposed outside of the inflatable balloon, and a flexible circuit. The flexible circuit includes a first conductor and a second conductor and is disposed outside of and carried by the outer surface of the inflatable balloon. The first conductor is in electrical communication with the first ablation electrode, and the second conductor in electrical communication with the first ultrasound transducer.