In this paper we describe an approach to interactively render ultrasound images for a transesophageal echocardiogram procedure. Our prototype features an animated 3D model of a human heart that is used to synthesize virtual ultrasound images in real-time. The user can control the probe and interact with the simulator via a GUI or with a haptics device. The ultrasound plane is rendered in a classical 2D view but can also be displayed in the context of the 3D heart model.