The present invention is a method for generating and displaying a 3D visualization of a cardiac-ablation balloon in a region of a living heart within a predefined 3D space. The method comprises: placing, inflating and positioning the balloon into the region； generating a 3D image of the region using a 3D medical imaging system； determining 3D location and orientation of the balloon in the region； based on the determined location and orientation, inserting a 3D balloon model into the predefined space to generate the 3D visualization； and displaying the 3D visualization on a display device. The method enables a user to visualize where cardiac ablation was applied within the region after the balloon has been moved from where the ablation occurred.
