Abstract. Four-dimensional phase-contrast magnetic resonance imaging (4D PC-MRI) acquisitions facilitate the assessment of time-resolved, 3D blood flow information. Vortex flow in the aorta or pulmonary artery is of special clinical interest, since it can be an indicator for different pathologies of the cardiovascular system. Qualitative methods commonly employ animated pathlines to depict the time-varying flow. Visual clutter is reduced via vortex flow extraction. Since vortices are often not present during the full cardiac cycle, parts of the animation show an empty vessel or flow that is not of interest. To exploit the given video length more efficiently, we propose Vortex Animations with Adaptive Speed (VAAS), which depend on the time- and view-dependent feature visibility. Collaborating experts considered our technique as useful for presentations, case discussions and documentation purposes. Four diverse datasets are presented in a qualitative evaluation.